Derek Arnold Ridgewell (May 9, 1943 in King's Park, Glasgow — 1982) was a former British Transport Police officer who was involved with a series of arrests followed by court cases in which it was later found that he had framed innocent people, and was eventually jailed for mail theft. Several of those convicted by courts based on Ridgewell's false testimony, including the Oval Four and the Stockwell Six, had their convictions quashed decades later. Ridgewell died in prison in 1982.