Historic Wales: a first look at the new map portal for Welsh heritage

 

I spend most of my time peering at Wiltshire, at sarsens, long barrows and LiDAR hillshades, so it's good to look over the border now and then and see how our Welsh neighbours do things. The new Historic Wales portal is in public beta until 1 December 2026, and its team is asking for feedback. So I've had a good look round.

What it is and who's behind it

Historic Wales calls itself "the map enabled portal for historic environment information in Wales". It's run by the Royal Commission on the Ancient and Historical Monuments of Wales (RCAHMW) and built on Esri's ArcGIS Hub and Experience Builder. What makes it worth having is that it brings the main Welsh heritage datasets together in one map:

• Cadw (cadw.gov.wales): Scheduled Monuments (I counted 4,236 records), Listed Buildings, Registered Historic Parks & Gardens and Designated Wrecks.
• Heneb (heneb.org.uk), the new body that now runs the regional Historic Environment Records: the HER of Wales, a huge 271,366 points, each linking to its Archwilio record.
• RCAHMW: the National Monuments Record of Wales, split into terrestrial and maritime layers, with each point linking to Coflein.

Think of it as Wales's answer to England's Heritage Gateway and Historic England's National Heritage List map, but on one map. That's the bit I envy. In Wiltshire I have the scheduling on one site, the HER on another and the old maps on a third.

The historic maps are the real treat

The highlight for me is the "Historic Mapping" theme. RCAHMW is working with regional archives and the National Library of Wales to digitise and georeference historic maps, and the beta already includes:

• Enclosure maps, funded by the Welsh Government. Breconshire, Carmarthenshire, Denbighshire, Flintshire, Glamorgan, Monmouthshire, Montgomeryshire and Pembrokeshire are already in, with the rest promised. You can lay Brecon Forest in 1819 or Malltraeth Marsh in 1861 straight over today's map.
• Admiralty charts from the UK Hydrographic Office, covering Milford Haven in 1830, the Swellies in 1872, Holyhead harbour and dozens more. Together they make up a new Maritime map.
• 6-inch Ordnance Survey maps from 1868 to 1892, courtesy of the National Library of Scotland, plus a promise of the 25-inch first edition. Anglesey and Flintshire are said to be online already.
• Historic county and civil parish boundaries for 1860–89 and 1889–1906. They're really handy, because so many old records are filed by the pre-1974 counties.

One tip, because it caught me (and others) out: ticking "Historic Mapping" on its own shows nothing. Every map sheet starts switched off, so expand the group, then the county or chart set, and tick an individual sheet. Each one only covers its own patch, so zoom to it. Once you know that, it all works nicely. The 1880s 6-inch sheet around Pentre Ifan is crisp right down to field level.

There's a swipe tool for comparing old and new maps, a measure tool, a choice of basemaps, layer reordering and transparency, and a table view. Each historic county also has its own preset map.

Trying it on two old favourites

Naturally I went straight for Pentre Ifan and Bryn Celli Ddu. Both turn up in all three datasets:

• Pentre Ifan Chambered Tomb is scheduled as PE008, with a separate scheduling, PE504, for the standing stone 120 m SSW. It's also in the HER (Dyfed records such as DAT1471) and in Coflein as NPRN 101450.
• Bryn Celli Ddu is AN002 to Cadw, GAT2694 in the HER and NPRN 93827 in Coflein. Around it sit a plough-levelled cairn, a cup-marked outcrop and an enclosure to the south-west. That's exactly the sort of landscape context I like to see.

One catch. The map viewer has no place-name or site-name search box that I could find. You either pan and zoom, or open the attribute table and filter it. If you know where you're going that's fine. A casual visitor typing "Pentre Ifan" will expect more.

Open data: better than it looks

This is where the geek in me cheered. The data layers sit on public ArcGIS Feature Services, so anyone with a GIS, a QGIS install or a few lines of code can query them directly. The site also says the open datasets from RCAHMW and Cadw can be downloaded from the platform. The NMRW layer carries a clear "Crown copyright: RCAHMW" credit, and the splash screen notes that copyright stays with each contributing body, whose terms apply. Records come in both Welsh and English. Cadw names have a Welsh form ("Beddrod Siambr Bryn Celli Ddu"), and the NMRW has Welsh fields too. There's also a Cymraeg button on the map and a separate Welsh-language hub.

No LiDAR here, though

As a LiDAR obsessive (I built LiDAR Lens for Wiltshire), I looked hard for a hillshade layer and didn't find one in this beta. Wales has good open LiDAR, and a hillshade under the HER points, with a swipe against the enclosure maps, would be a wonderful combination.

On the phone

It works on a phone. The tools sit along the top and the layer list slides up from the bottom. It's a bit cramped, though, and on a narrow screen the Cymraeg button sits over the toolbar. You also have to tick a terms box on every visit before the map will let you in. Both are fair beta niggles.

Verdict

It's an excellent idea: three national datasets, a quarter of a million HER points and a growing library of georeferenced historic maps, all in one free viewer with open services underneath. Add a search box and some LiDAR, and England would have a real reason to be jealous. The beta runs until 1 December 2026 and the team really does want comments, so if you have a Welsh corner you love, give it a try and use the Feedback button on the home page.

The Wiltshire Tornado of 1859: Thirteen Miles of Ruin

At about half-past one on Friday 30 December 1859 a tornado crossed north Wiltshire from Bowood Park, near Calne, to Ogbourne St George. This page is the companion to the short film Thirteen miles of ruin, with the sources behind each card.

The survey

Alfred Charles Smith, rector of Yatesbury, walked the whole track and published his account in the Wiltshire Archaeological and Natural History Magazine the following year. His figures: the storm "shaped its course for E.N.E., and took nearly a straight line in that direction for about thirteen miles, its breadth varying from 250 to about 400 yards". It took two or three minutes to pass any one place. He declined to estimate its forward speed, and no one was killed.

Smith also gave the geometry of the track: "a line drawn from the point of its commencement, one mile south of Calne, to that of its final disappearance at Ogbourn St. George, will very nearly pass through every farm estate and village enumerated above". That line is 12.8 miles long at a true bearing of 76°. The film draws exactly that line, with the places he names plotted beside it at their modern village centres. The red band is a diagram of a 300-yard breadth, not a surveyed boundary.

Smith's line from Bowood to Ogbourne; the red band is a 300-yard diagram, not a surveyed track. Map data © OpenStreetMap contributors.

Along the track

• Bowood Park: "where it broke off the large branch of an oak tree within the precincts of Bowood Park" — the first damage, about a mile south of Calne.
• Quemerford: "astonishing the inmates by bursting in the door and windows".
• Blackland: "swept down no less than one hundred and forty eight trees, some of great size and beauty".
• Hail Farm (now Hayle Farm): "a vast number of trees (amounting in all to about one hundred) were prostrated in every direction".
• Cherhill: "scarcely a tree stands unscathed … and scarcely a cottage retains its roof".
• Yatesbury, Smith's own parish: "taking up a heavy broad-wheeled waggon weighing 22 cwt., and lifting it over a high hedge". 22 cwt is about 1.1 tons.
• Winterbourne Monkton: "the old Rectory House, which had stood for many generations was altogether dismantled and became a ruin".
• Hackpen Hill: "even to the summit of old Hackpen … merely giving a passing salute by scattering a little thatch here and there".
• Temple Farm: "where it overturned several trees, and tore off the thatch of barns and other buildings".
• Ogbourne St George: "where it left its last parting token, by blowing down a small barn and two trees".

Why a tornado

Most trees fell eastward, along the track. The telling exceptions are the trees that fell towards each other: in a triangular meadow west of Cherhill, the trees on both long sides fell inward, and west of Yatesbury churchyard two parallel rows fell across the track towards each other. A few trees fell with their heads to the west, against the gale: two at Quemerford, one at Cherhill, one at Yatesbury. Eastern roof slopes were stripped while the western faces, which took the wind, stayed on. Convergent falls, backward falls and lee-side unroofing are what a rotating vortex explains. George Rowell, who spent three days on the track, could not see a whirl and preferred a downrush of air behind falling rain; four backward trees are a thin sample.

Rowell's sketch map of Cherhill; the arrows show "the direction of the wind, as indicated by the fallen trees".

Hail

At Bowood, Mr Spenser saw hailstones "nearly half an inch in thickness, and from two to three inches in diameter, star-shaped, with rays ranging from four to seven in number". Others were wedge-shaped, about three inches long, and fell clear of the rain.

Rowell's plate of the hailstones.

The weather that day

The NOAA/CIRES/DOE 20th Century Reanalysis (version 3) rebuilds weather maps for 1859 from surface pressure observations. At noon on the 30th the low had moved away to the north and southern England lay in a strong south-westerly. The tornado cannot appear in it: the nearest grid point to Yatesbury is 49 km (30 miles) away, and the track was a few hundred yards wide.

At the Radcliffe Observatory, Oxford, the register for the 30th reads "Stormy", wind south-west, rain 0.37 inch, anemometer 569 miles in the day, about 24 mph. The barometer was rising: 29.133 inches on the 29th, 29.422 on the 30th. The register does not mention the tornado. (Rowell's lecture gives 25½ mph from the west-south-west.)

How strong?

TORRO's list rates the event T6, Calne to Ogbourne St George, ST9769 to SU2074 (Brown, Meaden & Rowe 2013). Read against the TORRO scale, Smith's descriptions — mature elms uprooted, roofs removed in one piece, a garden wall laid flat, a loaded waggon lifted — fall in the T4 range, perhaps T5 if the Winterbourne Monkton rectory walls failed rather than only its roof. That is a reading of the descriptions, not a damage survey.

Notes on the film

• The track is Smith's stated line, not a route joined through village centres. Village points are modern centroids.
• No forward speed is given, because Smith gave none.
• Weather map: 20CRv3 ensemble mean, sea-level pressure every 4 mb, 10 m wind.
• Music: original.

Sources

• Smith, A. C. 1860. The Great Wiltshire Storm of December 30th, 1859. Wiltshire Archaeological and Natural History Magazine 6: 365–388.
• Rowell, G. A. 1860. A Lecture on the Storm in Wiltshire. Oxford.
• Burt, S. (ed.). Radcliffe Observatory, Oxford: meteorological observations 1853–1860. figshare, doi:10.6084/m9.figshare.13333925.
• Slivinski, L. C. et al. 2019. Towards a more reliable historical reanalysis: improvements for version 3 of the Twentieth Century Reanalysis system. Quarterly Journal of the Royal Meteorological Society 145: 2876–2908.
• Brown, P. R., Meaden, G. T. & Rowe, M. W. 2013. Tornadoes in Great Britain and Ireland to 1960: Part 3: years AD 1851–1875. International Journal of Meteorology 38 (378): 68–73.
• Map data © OpenStreetMap contributors.

A Mystery Square in the Stonehenge Landscape

 

Lidar Lens view

About 650 m north-north-east of Stonehenge, just north of the Avenue, there is a square. On the modern Environment Agency lidar it is very obvious: a ditched enclosure about 60 m across, centred at SU 1254 4278, with its sides running close to the grid. So what is it? I don't know, and that's rather the point of this post. It's a little mystery.

Who saw it first?

The first sign I know of was in 2010, when Simon Banton posted a relit image of the early lidar on his blog with a box over this spot marked "What's this then?" That post is no longer online, and I'm grateful to Simon for kindly supplying me with a copy.

Simon Banton's 2010 relit image of the early lidar, "What's this then?" Image: Simon Banton, used with thanks.

Part of something bigger

The Wiltshire & Swindon HER has a record here (MWI79347), from Michael Parker in 2024, for a feature seen on lidar: a circle about 140 m across with "an outer bank and inner ditch plus a raised area internally". I first thought that was something different, as it is round and much bigger. Having measured the lidar properly, I was wrong. The square sits in the middle of a shallow dish about 140–150 m across and 35–45 cm deep, with a low rise round its edge, clearest on the north, south and east. The hollows along the square's north and south sides are the deepest part of the dish, roughly 7–10 cm below the middle of the square and the ground just outside it. So Parker's circle and my square look like parts of the same feature, the circle seen at a broad scale and the square at a fine one.

What it isn't

I can't see it for certain on any of the early aerial photographs. That's perhaps not surprising, as it had been a cultivated, ploughed field.

Nor is it the wartime pillbox that shows on the 1943 USAAF aerial photographs (Currently offline). That stood about 230 m to the west-north-west, at SU 12320 42854.

And it doesn't show on the geophysics. The 2011 magnetometer survey covers the square fully, and there is nothing there (Darvill et al. 2013, Fig. 4B).

A 3D model, and 2001 against 2021

I've put the lidar into an interactive 3D model so you can look for yourself. You can exaggerate the height, move the sun, switch between hillshade, local relief and other views, and draw your own cross-sections. It holds two Environment Agency surveys at 1 m resolution, flown on 8 December 2001 and 4 April 2021. The square and the dish are in both, the same shape to within about a centimetre. Subtract one survey from the other and nothing has changed inside the square beyond the noise: less than 1 cm, when random patches of the same size across the field vary by about 1.5–2 cm. Whatever made it, it was there by 2001 and hasn't changed since.

So what is it?

It isn't a new discovery: Simon Banton spotted it in 2010, and Michael Parker recorded the circle in 2024. It's easy to miss because it is so shallow; it only stands out once the lidar is processed to pick out small changes in height. My first guess was something agricultural, a sheep pen or fold. Having measured it, I'm less sure. Sheepfolds on the chalk usually have a bank, often 0.4 m or more high, with a ditch outside it. This has no bank at the square, just shallow hollows inside a broad dish. Wartime or other military use, a natural hollow in the chalk, or something older all remain possible. If you know better, I'd love to hear.

Acknowledgements

Acknowledgements

Thanks to Simon Banton for a copy of his 2010 blog post.

References

• Banton, S. 2010. 'I love LIDAR and PTM', Novacaster Community blog, 4 Oct 2010 (no longer online; copy kindly supplied by Simon Banton).
• Darvill, T., Lüth, F., Rassmann, K., Fischer, A. & Winkelmann, K. 2013. Stonehenge, Wiltshire, UK: high resolution geophysical surveys in the surrounding landscape, 2011. European Journal of Archaeology 16(1), 63–93. doi:10.1179/1461957112Y.0000000025
• US 7th Photographic Group, 24 Dec 1943, sortie LOC122 frames 1022 and 1050 
• Wiltshire & Swindon HER, MWI79347.
• Environment Agency LIDAR, Open Government Licence.

Stonehenge Aerodrome in 1919: a 3D model from the US National Archives photographs

 Between 1917 and 1921 Stonehenge had an aerodrome for a neighbour, just to the west of the stones on either side of what is now the A303. Almost nothing of it survives on the ground, so I have built a 3D model of its buildings as they stood in early 1919. You can walk round it in your browser here:

Stonehenge Aerodrome, 1919: 3D model

The photographs

The starting point was a set of photographs taken on 20 February 1919 by Lt Sintzenich of the US Army Signal Corps, now held by the US National Archives (NARA). Each one is linked from the model, and here they are:

• 111-SC-153264: “View, looking east, showing a block of six hangars”, taken from the landing ground, with a biplane in an open shed.
• 111-SC-153265: “General view of landing field, with the Night Bombing School in the background”.
• 111-SC-153266: “View of hangars looking west”.
• 111-SC-153267, 111-SC-153268 and 111-SC-153269: three frames of the “Panorama of Stonehenge Camp, looking from southeast to southwest”.
• 111-SC-153276: a vertical view catalogued as the Night Bombing School. That was the other camp, by Fargo Wood, so its buildings are not laid out in this model.

How it was put together

Photographs alone don't tell you where things were, so the layout comes from maps. I traced 41 buildings from the Ordnance Survey six-inch map, Wiltshire LIV.SW, revised 1923, from the National Library of Scotland, and georeferenced it to the National Grid. Anything put up and taken down before 1923 may well be missing.

The big General Service sheds (the hangars) were set out from the RAF vertical photograph of 24 May 1921, reproduced in Martyn Barber's report Stonehenge Aerodrome and the Stonehenge Landscape (Historic England, 2014). It shows three coupled pairs of sheds end to end, with their ridges running north-east to south-west and the doors on the south-west gable ends. The north-easternmost pair, which I've called D, had gone by 1923, so it isn't on the OS map.

For the photographs, I worked back from the bearings of landmarks in each picture (hangar gables, a mast, huts, distant woods) to find where the camera must have stood. Several were taken from the roof of hangar pair B: the field views from its west corner and the camp panorama from its south corner. Photograph 264 was taken from the ground, out on the landing ground south-west of the row.

Using the model

• Photo pegs: the yellow pegs mark where each photograph was taken. Click one (or the numbered buttons) to see the photograph and stand where the photographer stood.
• Click a building to see its name and where the evidence for it comes from.
• Compass: bottom right, so you don't lose your bearings.
• Plan view with the 1923 map: open the plan with the OS overlay to check the model against the map.
• Shed doors: this view looks into the open shed of pair A, where a little biplane sits, as in photograph 264.

Drag to look around, use the wheel to zoom and right-drag to move.

Credits and corrections

Photographs: Lt Sintzenich, US Army Signal Corps, 1919, US National Archives, public domain. Map: OS six-inch Wiltshire LIV.SW (revised 1923), reproduced with the permission of the National Library of Scotland, CC-BY. Hangar layout from Martyn Barber's 2014 Historic England report. Model by Tim Daw.

This is my best reading of the evidence, and I'm sure there are mistakes. If you know the site, the photographs or the aerodrome's history, and something looks wrong, please tell me in the comments. I'll happily fix it.

The Flight of GX 10135 - Down the A303 on an August day, 1940

On 18 August 1940 a German reconnaissance aircraft crossed south Wiltshire with three cameras running. From near Mere it followed the line of the A303 east past Chicklade, Wylye and Yarnbury Castle to Winterbourne Stoke, passed Stonehenge, turned south over the Avon and ran down past Old Sarum to Salisbury. Its prints are in the US National Archives. Joined in order, they make a strip some 45 km long, and the films below fly it again. A companion to The Luftwaffe's Wiltshire and to the film of sortie GX 10484, flown three months later.

Sortie GB 956

NARA files the prints as box GX 10135. The titling strip on each reads GB 956 with the camera letter and the date, and each clock dial is pencilled "18.8." with the camera letter. The day is the one later called the Hardest Day of the Battle of Britain: the Luftwaffe made heavy raids on Kenley, Biggin Hill, West Malling, Hornchurch, North Weald, Ford, Gosport, Thorney Island and the Poling radar station. No record found links this sortie to those raids, and none records reconnaissance over Wiltshire that day.

Three cameras

Three cameras ran together, and all three survive for this stretch:

• L, a long lens of 502.48 mm: 17 frames, exposures 27–43, each about 5 km across on the ground.
• R, a second long lens of 505.13 mm aimed off to one side: 12 frames, exposures 19–30. Its frames overlap the L frames by only 5–25%, and they are not used in the films.
• S, a wide-angle camera: 9 frames, exposures 16–24, each about 13–15 km across. Each S frame contains three to five whole L frames, at roughly 2½ times less detail.

The L run has a gap. Over the Plain the aircraft turned through about 110°, and L 36 and L 37 do not overlap their neighbours. The S frames do: the nine of them join without a break from Mere to Downton, across the turn. So the films fly over the S strip and use the L frames for the close views, at Yarnbury Castle, Stonehenge and Salisbury Cathedral.

The nine wide-angle frames joined, north up. Places marked at their Ordnance Survey positions. Luftwaffe, 18 August 1940, NARA RG 373, GX 10135.

The camera clocks

On the L and R prints the dark mark near twelve is the hour hand; the minute hand is hidden under the pencilled date. The S clocks show both. Their minute hand moves from about 37½ on S 16 to about 44½ on S 24: roughly a minute between wide frames, and seven to nine minutes for the whole run. The hour hand stands just short of twelve. Neither the time zone nor whether the clocks were set together is stated on the prints.

The S-camera clock on the first and last frames, S 16 and S 24. NARA RG 373, GX 10135.

The centres of the S frames are 4.9–7.1 km apart, 45 km in all. Over seven to nine minutes that is a ground speed of roughly 300–390 km/h. If the film is 30 × 30 cm, as on GX 10484, the 5 km cover of the 502 mm lens puts the aircraft about 8 km above the ground. Both figures are estimates; no record names the aircraft or its unit.

Along the A303

The road was numbered the A303 on 1 April 1933, so it carried that number on the day of the flight. In 1940 it still ran through Wylye, bypassed in 1975, and through Amesbury, bypassed in 1969. For the first half of the run the aircraft follows it closely, which is why the films use it to keep the viewer oriented.

Yarnbury Castle

Yarnbury Castle, north up, from L 34. The A303 passes the southern edge of the hillfort. Luftwaffe, 18 August 1940, NARA RG 373, GX 10135.

The Iron Age hillfort lies beside the A303 west of Winterbourne Stoke. Next to it, white lines of freshly dug chalk mark army training trenches. The ground was commandeered by the Army in 1916, and on these prints the trenches are still bright, so the digging was recent.

Stonehenge, August 1940

Stonehenge, north up, from L 37. Luftwaffe, 18 August 1940, NARA RG 373, GX 10135.

Stonehenge falls on L 37, the frame at the turn. Beside the stones run the A344 and the old crossroads with the byway that was moved west in 1967. The 1917 aerodrome to the west closed in 1921; its buildings were demolished from 1927 and cleared by the early 1930s, and the Stonehenge Café and the custodians' cottages went in 1938. By August 1940 only the marks of these buildings remained. In high summer the grassland around the stones is pale and the tracks across it stand out, against the dull ground of the November photographs of GX 10484.

Old Sarum and Salisbury

After the turn the aircraft ran south down the Avon. Old Sarum, the Iron Age hillfort and site of the first Salisbury, passes on the way; beside it lay RAF Old Sarum, where No. 225 Squadron had been based since June 1940. The run ends over Salisbury, the cathedral and its Close in the middle of the frame, and continues south towards Downton.

Salisbury Cathedral and the Close, north up, from L 40. Luftwaffe, 18 August 1940, NARA RG 373, GX 10135.

Joining the frames

The nine S frames were matched on their common ground and fitted together in one adjustment; neighbouring frames agree to 2–4 scanned pixels for most pairs, 5–9 near Mere. Each L frame was then placed on the S strip, to within about a pixel of the S scan, so the close views drop into the wide flight in the right place. To label the films and set the north arrow, the strip was matched to modern imagery on some 750 field edges and hedgerows, to within about 70 m over most of it and 200 m at worst. Each part of the strip comes from one photograph only, so nothing is doubled at the seams.

Notes on the films

Three versions. The captioned film (3:05) names places as they pass and has short notes on the cameras, the road, Yarnbury, Stonehenge, Old Sarum and the cathedral. The director's cut (2:41) is the photographs alone, with a north arrow. The short (0:40) opens on Stonehenge, flies the A303 to Yarnbury and ends over Salisbury. All three run at four to five times real speed. The backs of the GX 10135 prints have not been scanned, so there are no interpreters' notes to quote. The music is original.

Sources

• National Archives and Records Administration. German Flown Aerial Photographs, 1939–1945. RG 373, series NAID 306065; file units GX 10135 SG and SK. catalog.archives.gov/id/306065
• English Heritage. Stonehenge in the 1930s and 40s: protecting the landscape. english-heritage.org.uk
• Historic England. Stonehenge Aerodrome and the Stonehenge Landscape. Research Report 7/2014. historicengland.org.uk
• Battle of Britain 1940. Sunday 18 August 1940. battleofbritain1940.com
• Wikipedia. A303 road; Stonehenge Aerodrome; Old Sarum Airfield; Yarnbury Castle; Wylye. en.wikipedia.org
• Daw, T. 2026. The Luftwaffe's Wiltshire. sarsen.org; map at wiltshire-luftwaffe.netlify.app

All photographs: Luftwaffe, 18 August 1940; US National Archives, RG 373, GX 10135, listed as Use: Unrestricted. Modern imagery (Esri) was used for matching only and is not reproduced. Frame matching, measurements and films: T. Daw. Methods and scripts: github.com/TimDaw37/wessex-films.

Verbum sapienti: a word to the wise

Professor Peter Kokelaar has earned a distinguished reputation as a volcanologist, and that is exactly why his recent essay arguing that the Stonehenge bluestones came "mostly by ice" is worrying. I raise it in the spirit of a friendly warning: a record built over a career deserves better than to be spent on claims that don't survive a first look.

The "Boles Barrow Bluestone" in Salisbury Museum - T. Daw

Take his "smoking gun", the Boles Barrow stone, which he calls a well-rounded erratic. Anyone can turn it round on the Sketchfab 3D model and see that it is squared off with dressed sides, worked by people rather than shaped by ice. Its link to the barrow isn't documented anyway. The Newall boulder, which he sets aside, has been discussed in detail by Bevins et al. (2023). 

To say there is no evidence for neolithic human transport of monoliths is just absurd. 

Even great minds can be led astray when they step outside their own field. Arthur Conan Doyle, creator of the most rational detective in fiction, staked his name on the Cottingley Fairies photographs, and that is now what many people remember him for. Peter is a far better scientist than that, and I hope he will step back before the ice-transport case becomes his Cottingley.

Disclosure: I am a co-author of Bevins et al. 2023.

The Flight of GX 10484

On 29 November 1940 a German reconnaissance aircraft crossed Wiltshire from the Avon gorge to the Hampshire border with two cameras running. Its 44 Wiltshire photographs survive in the US National Archives. Joined in order, the long-lens frames make a strip some 40 km long, and the film below flies it again: Avoncliff, Trowbridge, Bratton, Salisbury Plain, Stonehenge, Amesbury, Redlynch. For where these prints come from and every other Luftwaffe frame of the county, see The Luftwaffe's Wiltshire and its map.

Two flights, one page of links. This post is the flight of 29 November 1940, Avoncliff to Redlynch. For the flight of 18 August 1940, down the A303 to Stonehenge and Salisbury in high summer, see The Flight of GX 10135.

Sortie GB 1209

NARA files the prints as box GX 10484. Each print carries its own record. A titling strip gives the German sortie number, the camera and the date: GB 1209 L 29 11 40. A data panel gives the film number, the exposure number and the focal length of the lens. In the bottom corners are a clock and a level bubble.

Two cameras ran together. The L camera had a lens of 505.13 mm and took the close views, about 4.6 km square on the ground (exposures 109–135, film 1537). The S camera had a lens of 200.56 mm and took views about 11 km square (exposures 84–103, film 955), mounted the other way round. The two scales differ by 2.5, the ratio of the two lenses, so both cameras were looking down from the same height.

The backs show the paper and the custody. Each is printed on Agfa-Lupex paper, annotated in German pencil, typed "GX 10484" and stamped "Copied by Photo Rec. & Serv's Div, AAG, Hq. USAF". Exposure 131 of the L run and exposures 91 and 96 of the S run are not in the NARA set. The whole sortie runs to 254 frames, beginning off the Devon coast; the Wiltshire stretch is this post's subject.

A picture every fifteen seconds

The clock in the corner of each print shows the time of exposure. The centre of the dial is covered by a pencilled "29.11. L", but the ends of the hands are clear. The hour hand stands just short of two throughout. The minute hand reads 34.3 on exposure 109 and 40.7 on exposure 135: 26 exposures in about 6½ minutes, roughly one every 15 seconds. Each reading is good to about ±0.2 minute.

The S camera's clock runs 2.2–2.5 minutes ahead of the L camera's over the same ground, so the two clocks were not set together. Neither the time zone nor morning or afternoon is written on the prints; the film gives the clock readings and no more.

Joining the frames

Each L frame overlaps the one before by about 55%, and each is about 2.1 km further on. The frames were matched on several thousand common points per pair, each against its neighbour and the one beyond, and fitted together in a single adjustment that holds the scale steady from end to end. Most joins fit to within 2–4 m on the ground; over the Avon gorge, where the valley sides shift between viewpoints, to about 8 m. Each part of the strip comes from one photograph only, with a narrow seam between frames, so that hedges and trees are never doubled.

The scale comes from two known distances. On the long-lens strip, Bratton Castle to Stonehenge (23.8 km) gives 1.32 m of ground per scanned pixel. On S 102, Old Sarum to Figsbury Ring (5.2 km) gives 3.22 m per pixel.

The frames lean about 15° off the line of flight, the drift of an aircraft crabbing into a crosswind. At exposures 129 and 130, over Amesbury, they swing round by 12° and then 16°: the aircraft turned south over the Avon towards Clarendon and Redlynch.

What the interpreters wrote

The pencil notes on the backs name each frame by its map sheet and by the most prominent landmark in it. In every case read, that landmark is a prehistoric monument:

Back of print L 116: "Bratton Cas. b. Bratton sö Bristol / Bl. 32." Agfa-Lupex paper. NARA RG 373, GX 10484.

Print	Pencil note	Meaning
L 116	Bratton Cas. b. Bratton sö Bristol Bl. 32	Bratton Castle, near Bratton, south-east of Bristol, map sheet 32
L 126	Stonehenge Salisbury; "ca. 12 km nw. Salisbury"	Stonehenge written and struck out
L 128	Tumuli b. Stonehenge … nnw Salisbury Bl. 33	Barrows near Stonehenge, struck out
S 097	Yarnbury Castle nw Salisbury Bl. 33	Yarnbury hillfort
S 102	Old Sarum u. Figsbury Rings bei Salisbury Bl. 33	Old Sarum and Figsbury Ring

"Bl. 32" and "Bl. 33" are the same map-sheet numbers as the "Engl. Bl." references on the Luftwaffe target dossiers. None of the notes read names an airfield or a camp, though military sites on the Plain lie in the same frames.

Stonehenge

Stonehenge on L 127, 29 November 1940, shown as flown (top of picture to the south-east). The old A344 runs beside the stones. Luftwaffe, NARA RG 373, GX 10484.

Stonehenge falls on only one long-lens frame, L 127, close to its edge, and on S 098. The bank and ditch, the sarsen circle, the A344 beside the stones and the custodian's buildings are all clear. On the frames either side, 126 and 128, the interpreter wrote "Stonehenge" and then struck it out. The stones are not in either picture.

The aircraft

No record yet found names the aircraft, its unit or its crew. NARA's item records give none, and NCAP's Luftwaffe collection is uncatalogued at sortie level. The prints narrow it down. Lenses of 50 cm and 20 cm are the standard pair for German long-range reconnaissance, usually the Rb 50/30 and Rb 20/30 on 30 × 30 cm film. With that film, the ground each frame covers puts the aircraft about 7,800 m above the ground. Spacing and clock together give a ground speed near 500 km/h. Both fit a Ju 88 reconnaissance aircraft with a tailwind, or possibly a Do 215. Aufklärungsgruppe 123, Luftflotte 3's reconnaissance group in the west, was flying Ju 88s over southern England that month and lost two of them, at Parkstone on 14 November and at Coates on 24 November. All of this is an estimate; the film says so.

Notes on the film

The landscape film runs at about four times real speed and is turned so that the aircraft flies left to right. Each frame is captioned with its exposure number, NARA's nearest place name and its clock reading. It pauses on Bratton Castle and Stonehenge, which are shown from the original full-resolution scans. The missing exposure 131 is a short black gap. The short version opens on Stonehenge and then flies from Avoncliff to Bratton. The music is original.

For the purist: the director’s cut, the photographs alone at twice real speed. View on YouTube full-screen for the best experience.

A fascinating then and now comparison companion video:

Sources

• National Archives and Records Administration. German Flown Aerial Photographs, 1939–1945. RG 373, series NAID 306065; file units GX 10484 SG. catalog.archives.gov/id/306065
• National Archives and Records Administration. Target Dossiers Pertaining to the British Isles, 1938–1945. RG 242, series NAID 3371016. catalog.archives.gov/id/3371016
• National Collection of Aerial Photography. German Air Force (Luftwaffe), GB 551 NCAP/4. ncap.as.atlas-sys.com
• Luftwaffedata Wiki. Aufkl. Gr. 123 1940. luftwaffedata.co.uk
• Luftwaffedata Wiki. Aufklärungsgruppe Ob.d.L. luftwaffedata.co.uk
• Daw, T. 2026. The Luftwaffe's Wiltshire. sarsen.org; map at wiltshire-luftwaffe.netlify.app
• Daw, T. 2026. The Flight of GX 10135: 18 August 1940. sarsen.org

All photographs: Luftwaffe, 29 November 1940; US National Archives, RG 373, GX 10484, listed as Use: Unrestricted. Frame matching, measurements and film: T. Daw. Methods and scripts: github.com/TimDaw37/wessex-films.