No. 1 Photographic Reconnaissance Unit RAF

No. 1 Photographic Reconnaissance Unit (or 1 PRU) was a flying unit of the Royal Air Force, first formed in 1940.

History
On 24 September 1939, the Royal Air Force formally took over the "Heston Flight", a civilian photo reconnaissance unit headed by Sidney Cotton based at Heston Aerodrome. The unit had previously been contracted by MI6 to perform clandestine photographic reconnaissance over Europe, using civilian-registered Lockheed 12A aircraft. The Flight was redesignated several times, first on 1 November 1939 as No. 2 Camouflage Unit, then on 17 January 1940 as the Photographic Development Unit, then on 18 June 1940 the Photographic Reconnaissance Unit, and finally on 14 November 1940, No. 1 Photographic Reconnaissance Unit.

The unit was equipped with a variety of aircraft modified for the photographic reconnaissance rôle, including Supermarine Spitfires, Bristol Blenheims, Lockheed Hudsons and de Havilland Mosquitos.

On 18 October 1942, 1 PRU was disbanded and the individual Flights of the Unit were redesignated as five separate squadrons, Nos. 540, 541, 542, 543 and 544 Squadrons.

On 1 June 1982, the Unit was revived at RAF Wyton when No. 39 Squadron was disbanded and some of its English Electric Canberra PR.9 reconnaissance aircraft were transferred to a newly formed No. 1 Photographic Reconnaissance Unit. The Unit reverted to its previous identity on 1 July 1992, when it was renumbered No. 39 (1 PRU) Squadron.