Ref No: GB 551 NCAP/1
Extent: c. 280,000 aerial images. Exact physical extent to be calculated following completion of a barcoding project in 2009/2010.
Title: Royal Air Force: National Air Photograph Survey (Scotland).
Description: Vertical and oblique aerial images of locations throughout Scotland from the National Air Photograph Survey of Great Britain and Northern Ireland plus associated sortie plots. The imagery was created by the Royal Air Force between 1944 and 1950.
Access Conditions: Open. Accessible via search room and Paid Search Service.
Copyright: Standard licence terms for use apply.
Finding Aids: GIS catalogue in search room provides access to digital copies of the original sortie plots.
Physical Description: Aerial film / aerial prints / paper sortie plots. Aerial imagery is mostly 8.5 x 7 inches (220 x 175mm) / 9 x 9 inch (230 x 230mm) / 5 x 5 inch (128 x 128mm).
Creator Name: Royal Air Force.
Administrative History: In the immediate aftermath of the Second World War (1939-1945) the Air Ministry agreed that the Royal Air Force (RAF) would undertake OPERATION REVUE, an aerial photographic survey of Great Britain and Northern Ireland. The survey was designed to assist the Ordnance Survey (OS) in revising its maps of the country but there were also to be benefits for the Ministry of Health and the Department of Health for Scotland, in the field of town planning, and the Ministry of Transport, for road building. Designed to produce stereoscopic vertical cover at 1:10,000 scale, with larger scales available for urban areas, the survey was initially scheduled for completion by the end of 1947, but some areas were re-flown in 1948-1950 to rectify deficiencies caused by cloud cover or camera failure. Around 500 sorties were flown over Scotland during the survey, resulting in the collection of over 280,000 photographic images.
The Davidson Committee, set up in 1935 to examine the future operation of the OS in the face of mounting pressure for maps, recommended that OS have the services of a dedicated aerial photography unit. The Second World War intervened, and when hostilities ended the RAF was asked to undertake the survey instead. It was well placed to do so, with many surplus aircraft and trained aircrew available for the task, and an efficient processing and cataloguing operation in place on the ground. A start to the survey in Scotland had unwittingly been made in 1944, as a few small-scale survey sorties had been flown by No.8 Operational Training Unit (OTU) from RAF Dyce, Aberdeenshire, between September and November of that year, with a variety of other units, including No.542 Squadron and the Photographic Reconnaissance Development Unit (PRDU), making small contributions during 1945. To offer an enlarged and sustained post-war effort, two squadrons were formed in the photographic reconnaissance role on 1 October 1946 under the direction of the Central Photographic Establishment (CPE) of Coastal Command: No.58 Squadron, equipped with Avro Ansons and de Havilland Mosquitoes; and No.82 Squadron, formed from a detachment of No.541 Squadron, equipped with Avro Lancaster PR Mk.1s, Supermarine Spitfires and Airspeed Oxfords. No.540 Squadron followed on 1 December 1947, with Mosquitoes, having already acquired a good record for photographic reconnaissance work while operating from Scottish bases during Second World War. Indeed, this unit had already added a complete aerial survey of France to its credits in 1945. Supermarine Spitfire PR Mk.19s of 'A' Flight No.541 Squadron were added to the national survey in May 1948 and maritime reconnaissance Avro Lancasters of No.120 Squadron obtained cover of the Western Isles and Orkney in 1948, while based at RAF Leuchars, Fife.
Aerial surveying in peacetime conditions is rather different from photographic reconnaissance (PR) during wartime. In peacetime operations, aircraft are able to maintain a straight and level course at an economical cruising speed, cover an area of ground in a predictable pattern and fly at the optimum altitude required for the cameras and lenses carried. In addition, the types of aircraft required for wartime reconnaissance are not necessarily the best platforms for peacetime surveying. The Avro Anson, for example, would not have survived wartime PR operations over enemy territory, but proved to be an effective and economical aerial survey platform in the post-war period. Wartime aircraft such as the Spitfire and Mosquito were extensively used to collect oblique images, however, as they were well equipped with forward- and side-facing oblique installations.
The main cameras used in the survey were the F49 and F52, which could be fitted vertically with a range of lenses from 6- to 40-inch focal length. The film used was of a larger format than had been used previously, with individual frames measuring 9 x 9 inches (230 x 230mm) in the F49 and 8.5 x 7 inches (220 x 175mm) in the F52. For oblique sorties, the F24 camera was the general choice, often fitted with an 8-inch lens, giving frames of 5 x 5 inch (128 x 128mm) size. Camera lenses were kept free from frost and condensation during a sortie by having hot air from the engines blown over them.
While the RAF made great efforts to provide the cover required, it experienced some difficulties due to unsuitable aircraft, outdated equipment and the continual rotation of aircrew.
Ranging in date from 6 September 1944 to 2 July 1949 the prints are panchromatic. Vertical cover is held of all of Scotland, with oblique cover of many other, mostly urban, areas.
Cover consists of individual sorties or runs of photographs taken on various dates, with a corresponding map plot of each sortie providing a geographic key to the locations covered by it. For oblique sorties, the line of flight is drawn on the maps, with print numbers indicated on the left or right of the line depending on whether a port- or starboard-facing camera was mounted. For forward-facing oblique cameras, the line of flight is annotated with an arrow showing the direction of flight, and print numbers are given at each end of the line. At the edge of each sortie plot is a key which gives the title of the sortie, the date of photography, the height of the aircraft above sea level, the focal length of the cameras used, the time of day photography began, the number of photographs taken by each camera, and the nominal scale of the images (vertical only). In many cases the surnames and ranks of the aircrew and the serial number of the aircraft are also given. Any frames hidden by subsequent runs in the same sortie are noted at the edge of the map and areas covered by cloud, cloud shadow or mountain shadow are shaded.
Frame numbers are prefaced by a letter code which identifies the position of the camera within the collecting aircraft. For oblique photography, camera installations are identified by the following prefixes: P (Port), S (Starboard), PFFO (Port Forward-Facing Oblique) and SFFO (Starboard Forward-Facing Oblique). Very occasionally, the preface N (Nose-mounted Forward-Facing) is used.
No original negative film from 1945-49 is held, as its cellulose nitrate composition becomes extremely unstable with age and it was deliberately destroyed after copying onto a safer acetate-based film during the 1950s. The rolls of film held from each sortie are either duplicate positives made from the original negatives or duplicate negatives made from duplicate positives. Worthy of note are the clearing shots made at the beginning, and often also at the end, of each sortie. These images, at either end of the film proper, often show aircraft, airfield buildings and airmen at work, captured on film when the shutters of obliquely installed cameras were triggered several times to check that film was loaded and winding properly prior to a sortie, and to finish the film once the aircraft had returned to base. Some of the images from oblique cameras show photographic reconnaissance de Havilland Mosquitoes, Supermarine Spitfires, Avro Ansons and Avro Lancasters parked in hangars and at dispersals, with attendant airmen and vehicles. Also of note are the film reports often found in the film cans, which give details of the types of cameras used, the size of lenses fitted, the number of frames taken by each camera and any atmospheric or technical problems encountered during the sortie. Each report is signed off by the technician responsible for fitting and removing cameras and films, by the non-commissioned officer in charge and by the navigator or pilot of the aircraft.
Custodial History: Held from creation by the Scottish Office. Within the Scottish Office it was held by the Department of Health for Scotland until its 1962 transfer to the Scottish Development Department. Within these departments it was held by the entity variously known as the Air Photograph Library / Air Photographs Unit. The collection was transferred to RCAHMS in 1993.