Agatha
You may be interested in this photo I took at Biggin Hill ln 1954 of Boulton Paul Balliol T2, serial Number WG180 based at Middle Wallop.
It was taken during the 1954 Royal Observer Corps 'Recognition Day' that was held annually at Biggin Hill when a variety of RAF, RN and USAF aircraft were flown in so members of the Royal Observer Corps could see up close the friendly aircraft they were expected to recognise in the air.
This aircraft was from 288 Sqn at Middle Wallop whose Balliols provided target aircraft for training all-weather fighter crews using Brigands of No.228 OCU at Colerne and also for the training of student Fighter Controllers at the Fighter Command Control and Reporting School also at Middle Wallop.