by Kevin Wright
In 1947 the Avro Anson was selected for Corridor flights for two reasons. First, the type was in widespread use in Britain and mainland Europe as a communications aircraft and so was a common sight. Secondly, some Ansons had already been modified for photographic reconnaissance work and used to update urban mapping of the UK to assist with post-Second World War reconstruction plans. The Ansons used on Corridor operations initially had a single vertically mounted US-origin K-17 camera with a 6in lens and a single vertically mounted F.24 both of which were mounted on the right hand side aft of the main wing spar that looked out through two holes in the cabin floor. When not in use these camera apertures were covered inside by two sheets of plywood, which were then hidden by the carpet. In 1953 or 1954 this antediluvian arrangement was replaced by a split-pair of F.52 cameras with either 14in or 20in lenses and a single port (left) facing oblique with a 36in lens. This camera fit remained extant until replaced by Pembrokes from 1956, although some Ansons soldiered on until 1957. During the Anson-era the crew consisted of the pilot, navigator, an Intelligence Corps major from the APIU (BAOR) and a SAC photographer. The photographer was responsible for operating the cameras under the direction of the major who wore other regimental titles when he was on the flights.6
The only purpose-built PR aircraft used in the Corridors were the Spitfire PR.XIXs of II (AC) Squadron operating from Bückeberg for a short time from 1950. They were used on ‘unofficial’ flights to photograph Soviet Zone airfields for indications of any build-up of aircraft that could be a precursor to a further Berlin blockade. The Spitfires operated with a split-pair of F.52 cameras with 36in lenses sometimes used in an oblique mode by banking the aircraft. Often flown above 10,000ft, the Spitfires were not part of the British Corridor programme but assigned for that specific task.
2TAF Communications Squadron and its predecessors were based at RAF Bückeberg until 1954 when the squadron moved to RAF Wildenrath and became heavily involved in British Corridor operations. In 1955 it possessed approximately twelve Anson Mk.12/19s and 21s, a Valetta, a Devon, a Prentice and some Vampires. From January 1956, the Ansons were gradually replaced by Percival Pembrokes. The three Pembrokes initially operated CASEVAC missions between Germany and England. On 1 January 1959, 2TAF Communications Squadron was renamed the ‘Royal Air Force Germany Communications Squadron’ (RAFG Comms Sqn) with Pembrokes, a Devon, a Heron and a Valetta used by the C-in-C RAF Germany. On 4 February 1969 it became 60 Squadron RAF.7
Stronger Political Controls
Following the 1956 Crabb affair, PM Anthony Eden had instigated an urgent review of UK intelligence operations. A key outcome of the review was greater direct exercise of political control over all future British intelligence operations.8 Another issue was the agreement between the naval and air intelligence staffs with diplomats made in July 1955 on ‘Political Approval for Certain Intelligence Operations’, which essentially gave the services blanket approval for activities against ‘opportunity targets’, with the main restrictions being on aircraft and ships not entering the territorial waters (or airspace) of another state and ‘taking reasonable precautions to avoid incidents’. The review suggested that these procedures be significantly tightened by requiring more detailed scheduling, the necessity for individual mission approvals from senior military and government-level officials, coupled with the introduction of greater safety distances.9
In 1955 Federal Germany became a sovereign state and the three Allies’ military governments were withdrawn. Formal diplomatic relations with Germany now centred on Bonn, designated as the West German capital until some future unspecified reunification. This normalisation of diplomatic relations required formal changes to the approval procedures for Corridor and BCZ operations. The Foreign and Commonwealth Office (FCO) became more actively involved in the policy and approval processes as London took over responsibility for them. Berlin continued to be treated somewhat differently as it officially remained under four-power occupation status until 1990.
The submission to government for general approval to mount regular air photographic operations in the Air Corridors and BCZ was initiated by the Air Reconnaissance Sub-Committee of the Joint Air Reconnaissance Intelligence Board (JARIB) and ‘Ops Recce’, RAF, at the Air Ministry/MoD in London. The submission always included the term ‘Overflight Clearance’ and included a Defence Intelligence Staff (DIS) Risk Assessment. These submissions were regularly updated and reviewed on a biannual and later annual basis for the duration of operations. The submission was led by the MoD at two-star (air vice-marshal) level and incorporated FCO views and advice. The agreed combined submission would then be sent to the JIC in London for its recommendation. It was the JIC’s responsibility to place the proposal before a Cabinet sub-committee comprising the prime minister, Foreign Secretary, Secretary of State for Defence and Secretary of State for Air with the Chairman of JIC London in attendance. They would give the final broad approval for the continuance of operations and specified the ministerial rules under which they would operate. The approval also specified the annual maximum number of flights for both Corridor and BCZ operations. The high level of political approval required shows how sensitive the operation was considered.
This broad political approval was kept under constant review to capture changes to the political or military situation in Germany and internationally. This sometimes required modification to the devolved authorisation or the curtailment, or suspension, of individual operations for short periods. Such decisions would usually be approved by the Cabinet sub-committee acting on the JIC’s recommendation. International tensions with the Soviets affected the programmes, with constraints probably being at their most severe between 1960 and 1962.10
Following the loss of Powers’ U-2 on 1 May 1960, the British immediately suspended all photographic collection flights in the Berlin Corridors and BCZ, although normal Pembroke transport and Chipmunk training flights continued. By the autumn of 1960 pressure was building for the resumption of UK photo missions along both Corridors and inside the BCZ – especially to gather more information on what was viewed as the burgeoning SA-2 Guideline threat.11 On 14 December 1960 a ministerial meeting, chaired by PM Macmillan, agreed to the cautious resumption of sorties with two Corridor and two BCZ sorties which were to be completed by the end of February 1961. As one note records, the ‘photographs were well received by the US intelligence agencies’, with whom the British shared their imagery.12 Similar requests for flights continued to be submitted on a regular basis through 1961, and although nineteen corridor flights were authorised, only nine were completed because of time, technical and weather constraints. For the Americans, although U-2 and other overflights were under Administration control, Corridor and BCZ flights were regarded more as ‘routine operations’ and had continued largely unaffected. Following the 1960 U-2 and RB-47 shootdowns, successive British Cabinets were much more cautious than the Americans, and were prepared to cancel missions to avoid even the slightest possibility of potentially embarrassing incidents.13
The August 1961 construction of the Berlin Wall resulted in the serious curtailment of some intelligence sources and the complete loss of others, especially HUMINT ones. As a result the Corridor and BCZ Chipmunk programmes assumed a greater importance in intelligence collection. Requests for further flights took on a new imperative, particularly when some unsubstantiated reports were received of East German forces being present in East Berlin and troops deployed from mainland Russia rumoured to be gathering east of the city. This time there was to be no step back. The USA itself had ramped up Corridor and IGB flights as the tensions rose but these revealed no massing of Soviet forces preparing to take West Berlin.14 Requests for the continuance of reconnaissance flights increased as the crisis in Berlin spiked during late October 1961, with US and Soviet tanks facing each other at Checkpoint Charlie. However, the tensions persisted; in February 1962 the Soviets attempted to restrict airspace resulting in the activation of the ‘Jack Pine’ HQ for some time to susta
in the Allied presence in the Corridors.15
The Easing of Controls
The direct political control of individual flight authorisations gradually eased during 1961, passing to the General Officer Commanding (GOC) Berlin for Chipmunk BCZ flights and C-in-C RAFG for Pembroke Corridor and BCZ missions. This was formalised in a minute from Sir Norman Brook in April 1962, specifying a maximum limit of two Chipmunk and one Pembroke flights per week, and detailing where and how they were to be conducted.16 Local discretion over the number of flights was soon extended to allow both GOC Berlin and C-in-C RAFG to authorise additional missions if local circumstances warranted it.17 The flights went ahead successfully, although not everyone in government was happy about them. Harold Watkinson, then Defence Minister, commented on one early request, ‘I doubt myself whether the risk is worth taking. Using the Corridor for spy flights would be a good card for the Russians.’18
In April 1962 a blanket clearance was granted for one Pembroke and two BRIXMIS Chipmunk flights per week that could be authorised by C-in-C RAFG and GOC (Berlin) respectively with no further recourse to London. By August 1962 this had changed and the C-in-C RAFG was permitted to authorise up to two additional Pembroke flights per week providing the situation warranted it, again without further authority.19 Before an individual flight was authorised in Germany the relevant diplomatic sections at the British Embassy in Bonn and/or BMG in Berlin had to be consulted. This mechanism of London controlling overall approval for the annual numbers of flights remained in place, with periodic modification, until the cessation of operations in 1990. Besides political nervousness, there were also some worries at senior command levels over who would be held responsible if something went wrong with a flight. This served to colour decisions which perhaps became over-cautious at times.
The experiences of the Crabb and 1960 U-2 incidents became firmly entrenched in the British political psyche and approval processes for Corridor and BCZ operations. In subsequent years the approach was generally cautious. Short suspensions were often made on either side of senior British ministerial or state visits to and from Germany, the Soviet Union and Warsaw Pact states. British flights were often suspended for a few days during US presidential visits and elections at American request, and British flights were curtailed during General Election campaigns for fear of an incident. They would be quietly resumed after the new government had come into office in London and had been informed of the overflight programmes and given assent to their continuation.
RAF Pembroke Operations
Our account of RAF Corridor operations really starts from around 1960 when the accepted norm was that only transport and training aircraft were allowed to use the Corridors and BCZ airspace. The Pembroke clearly met those requirements. According to a 1969 JIC paper the Pembroke was primarily ‘selected for clandestine photography because it is in current use as a communications aircraft in RAF Germany’.20 Operating from RAF Wildenrath, these venerable Percival Pembrokes led a ‘dual existence’, flying very different types of mission. Some were configured as VIP and communications aircraft, shuttling equipment, senior officers and military personnel around Western Europe. Three Pembrokes led the more clandestine existence of regularly prowling along the Air Corridors and around the BCZ, photographing Soviet and East German targets. Intertwining overt and covert tasks in the same unit meant it was possible to disguise, to a certain extent, the true role of the camera-equipped aircraft.
Photo-Equipped Pembrokes
Six Pembrokes were originally built for photographic duties in the Far East. They flew with 81 Squadron, a specialist photo-reconnaissance unit used mainly for survey work. The unit based at Seletar in Singapore, with detachments to Labuan, Butterworth and Kai Tak, operated its Pembrokes between December 1955 and August 1960. Ray Dadswell was a photographer responsible for fitting and loading cameras in Pembrokes and Meteors with 81 Squadron between 1957 and 1959. He recalls that at that time the aircraft usually carried either F.24, or two F.52 cameras and sometimes an F.49 for survey work. The F.52s were usually fitted amidships as a split-pair. One camera pointed a few degrees to port and the other a few degrees to starboard. The optical flats through which images were taken were covered by manually operated twin doors.21 A further two (XL953 and XL954) were converted from C1 airframes to C(PR)1 versions on the production line.
Everything about the use of the Pembroke for Corridor photographic operations was a compromise. Political caution, together with financial parsimony, meant a different aircraft type was unlikely to be procured for use in Germany for a very long time. Perhaps the Hallmark programme even extended the life of the communications Pembrokes as the RAF delayed replacement of the camera-equipped aircraft in Germany? As the airframes approached the end of their lives and spares became difficult to source, the Pembroke was finally retired and the Andover replaced it in RAF Germany firstly in the VIP role.
The original equipment ‘fit’ for the photo-reconnaissance Pembrokes in Germany was similar to those of the Ansons they replaced:
• A port-facing F.52 with either a 36in or 48in lens
• A split-pair of two F.52s with 14in or 20in lenses
• A vertical F.49 ‘mapping camera’ with a 6in lens.
The fit did not produce the quality of imagery that many sought – achieving satisfactory results only as far as 2 to 6 miles from the aircraft and not the desired 10-plus miles. Among the National Archive files, one very detailed paper, and accompanying technical commentary, illustrates the shortcomings of the original Pembroke camera fit. Problems included the lack of ‘image motion compensation’ for the F.52s, which limited the conditions in which they could be used at low level in good weather conditions, and even then the resolution was not high. Equally there were concerns that camera vibration would be a significant issue in achieving high-quality imagery. It recommended improvements that could be made without having to move to a new aircraft type.22
RAF post-Second World War aircraft camera development had concentrated on equipment suited to either extremely high-level or low-level flying. Cameras optimised for the Corridor operating altitudes (3,500–10,000ft) were largely neglected. The document recommended a number of short-term solutions pending the procurement of a more suitable aircraft. The recommendation was to fit five F.96 cameras mounted in a special frame anchored to the aircraft’s floor and ceiling. Three of the F.96s, with 12in lenses, were to be in a ‘fan’ configuration and two F.96s with 48in lenses in oblique mounts. This F.96 camera fit was originally developed and flown in a Hastings of 51 Squadron. The Hastings had been proposed as a Pembroke replacement but the programme was cancelled during an early 1960s Defence Review. In the Pembroke the oblique cameras looked out of the cabin windows – third from the front on the port side and second from the front on the starboard side – and this necessitated the replacement of the standard windows by very expensive ‘quartz’ windows to minimise distortion. To operate the cameras, appropriate control panels and some wiring changes also had to be made. The cameras were fitted with 250ft and 500ft film magazines. The weight of the F.96 camera fit plus the crew and fuel brought the Pembroke close to its maximum take-off weight, which limited its range, especially during hot weather. Consequently some flights to Berlin could require an interim refuelling stop, at RAF Gütersloh for Northern Corridor and at the USAF Bitburg or Rhein-Main ABs for Southern Corridor missions. As more flying restrictions (weight increases and age) were imposed on the Pembroke, one of the oblique cameras, usually the left-facing one, was removed during the summer months. This may have allowed the aircraft to fly direct to Berlin without a fuel stop.23
To improve imagery quality, special camera mountings that minimised airframe vibration were essential. The Pembroke had a very low ground clearance so sliding camera hatches were installed on the fuselage underside to preserve an element of secrecy and protected the lenses. The equipment choices were all compromises, based on what was readily available in RAF equipment stocks and could fit into the narrow c
onfines of the Pembroke’s cabin.24 In addition to these ‘short-term’ measures, a long-term solution to replace the Pembroke with a Vickers Varsity was discussed, although soon rejected on cost grounds and the availability of airframes for conversion.25
The RAE suggested a total modification cost of £150,000 for three aircraft, which pales into insignificance compared to the US investment in its Corridor operations. The Pembrokes clearly lacked the capabilities of the highly specialised US platforms, but as an investment in ‘aerial espionage’, they generated a good political and military return for many years. In the original case for updating the Pembroke camera fit, one argument was that modification would improve the UK’s contribution to imagery collection, thus enabling the Americans to justify their continued exchanges with the British. However, the JIC made the point that because US–UK armed forces and intelligence agency relationships were so strong, the UK contribution of Corridor material probably made little difference in influencing the continued supply of US Corridor imagery to the British.26
On 10 January 1963, the modification programme was approved in principle. The most important part of the project was the design and installation of the special vibration-reducing camera mountings. That task was given to Fairey Air Survey Limited, which had the appropriate security clearances and was also involved on the secret camera fits for the ‘V’ bomber force.27 The modification of the three aircraft was to be carried out under a contract issued in support of ‘Modification 614’. Work began at the end of 1963 to modify three Pembrokes – XF799, XL953 and XL954 – for photographic work. These Pembrokes would become known in Germany as the ‘in fit’ aircraft. An additional aircraft – XF796 – flew in the role until 1975, but with the less capable original camera fit.
