used exclusively by No. 414 Squadron RCAF to replace its TAC-R Mustangs. The same conversion was used on F Mk XIVe Spitfires to make FR Mk XIVe Spitfires used exclusively by No. 430 Squadron RCAF. T Mk IX and TR 9 (type 509) Although there were wartime conversions of the Spitfire into a two-seat trainer including the one-off modification of a Mk Vc by RAF no. 261 Squadron and a Mk IX converted for use as a trainer by the Soviets, the two-seat Spitfire trainer was primarily a postwar programme. In 1946, a Mk VIII (MT818) was the first Vickers-built trainer built as a demonstrator, but in 1948, 10 Spitfire T Mk IXs, were exported to India. In 1951, a further six TR 9 trainers were converted from the standard Mk IX to train pilots for the Irish Air Corps (IAC) Seafire fleet. The Spitfires provided transition training that included gunnery practice since the type was equipped with two .303 Browning machine guns, one in each outer wing bay. Most of the TR 9 aircraft passed to the ground technical training school at Baldonnel where they were used as instructional airframes for the training of aircraft engineers for the Air Corps. Four of the IAC aircraft survived and two went on to join the warbird fleet in the 1970s and later. In total, 5,656 Mk IXs were built, 561 by Supermarine and 5,095 by Castle Bromwich. Production of the Mk IX ended in April 1945 and, in combination with the Mk XVI this "compromise" was produced in larger numbers than any other Spitfire variant. PR Mk X and PR Mk XI (types 387, 365 and 370) When development started on new Merlin 60 powered Spitfires, both the Mk VII and VIII were to have photo-reconnaissance (PR) variants. On 21 April 1942, an order was placed for 70 aircraft, provisionally designated PR Mk VIII. Based on the revised MK VIII airframe these aircraft were to be powered by Merlin 61s and were assigned serial numbers LV643–681 and LV726-756. The Spitfires bearing these serials were eventually built as Merlin 66 LF Mk VIIIs. A policy change resulted in the pressurised PR variant of the Mk VII being renamed PR Mk X (type 387). This version followed the PR Mk XI into production and was based on the Mk VII airframe with PR Mk XI wings and camera installation. It had the pressurised