An aircraft crash near Canons Ashby House was due to engine failure after the pilot performed a steep left turn.
The Air Accidents Investigation Branch investigated the crash, involving a 1930 Gipsy Moth on August 12.
The pilot of the plane was Giles English. He and his passenger, an 11-year-old boy later named as Oliver Nuttall, were left with “serious injuries”.
The report, following an interview with Mr English, states the engine had been “consistently reliable” and there was no identified reason for it failing.
The report states: “The aircraft was performing a steep turn to the left when the engine stopped.
“It entered a spin and, while the pilot was able to recover from the spin, during the subsequent forced landing the aircraft struck a grass bank and was extensively damaged.”