In The Flying Crusaders, Mancroft Castle was the stately home belonging to Sir Giles Mancroft, who was one of the early pioneers of aviation. Set in fen country, somewhere in Lincolnshire, Cambridgeshire, Norfolk or Suffolk, the castle housed a collection of aircraft from the earliest days of aviation. After the Second World War, Sir Giles, facing financial diffciulties, was forced to auction off most of his collection. However, Biggles' intervention resulted in the recovery of a hitherto stolen painting which brought Sir Giles a financial windfall, allowing him to keep his castle as well as his own vintage aircraft, the "Flying Crusdaer".
Mancroft Castle is a fictional location.