The wonderfull picture below was kindly provided by Richard Heseltine and is from a Britax press release. The original caption says: "Amateur racing driver Allan Staniforth in his home-made 'Terrapin-Min' with which he broke 9 speed records at Elvington, Yorkshire on October 6th (according to my information it was the 5th-JB). Britax produced a special set of racing harness for the car, which, for the first time, incorporated a pair of thigh-support straps." Thanks again, Richard!
Allan Staniforth and his 'Terrapin-Min' record car at home in Yorkshire
Picture provided by Richard Heseltine