National Air Photograph Survey
- Reference:GB 551 NCAP/8/1/2
- Dates of Creation:1944 - 1950
- Name of Creator:
- Language of Material:English
- Physical Description:280000 aerial photographs
Scope and Content
Vertical and oblique aerial images of locations throughout Scotland and associated sortie plots. Photographs were taken between 6 September 1944 to 2 July 1949.
Administrative / Biographical 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 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 in this collection 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.
Arrangement
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.
Access Information
Open. Imagery is accessible by appointment via the NCAP website, search room and Paid Search Service.
Other Finding Aids
GIS index in the search room and website provides access to digital copies of sortie plots.
Physical Characteristics and/or Technical Requirements
5-inch and 9-inch wide rolled aerial film / 5x5-inch, 8.5x7-inch and 9x9-inch prints / sortie plots.
Conditions Governing Use
Standard licence terms for use apply.
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.
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.
Related Material
The aerial photographs and sortie plots from the National Air Photograph Survey of England, Wales and Northern Ireland are held by:
- Historic England Archive, The Engine House, Fire Fly Avenue, SWINDON, Wiltshire, SN2 2EH. Tel: 01793 414600, E-mail: archive@HistoricEngland.org.uk
- Royal Commission on the Ancient and Historical Monuments of Wales, Ffordd Penglais, Aberystwyth SY23 3BU. Tel: 01970 621200, E-mail: nmr.wales@rcahmw.gov.uk
- Public Record Office of Northern Ireland, 66 Balmoral Avenue, BELFAST BT9 6NY, Northern Ireland. Tel 028 9025 5905, E-mail: proni@dcalni.gov.uk
Bibliography
RCAHMS (2004), Catalogue of Royal Air Force oblique aerial photographs 1945-9 held in the collections of RCAHMS, Scotland from the Air 1939-49, volume 3, ISBN 1-902419-43-X
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