In The Case of the Stolen Aircraft, Wing Commander Lyall was the Provost Marshall of the R.A.F. He informed Air Commodore Raymond and Biggles about two aircraft which had been stolen from R.A.F. Training Stations. First, a Westland Lysander had been stolen from a station in Essex and had ended up as a wreck in the Yorkshire moors. Second, a de Havilland Mosquito had disappeared from another station and ended up in a farmer's field in Lincolnshire about 40 miles away.