In the 1950s Rover was regarded as the staid wheels of the well-heeled. They went about life in their own snooty way, and you would hardly have guessed the company had a tiger by the tail. It was called JET 1 and was the first gas turbine-powered car. During the late stages of the Second World War, Rover had been intended as the main producer of the new Whittle jet engine for aircraft while Rolls-Royce was working flat-out on Merlin and Griffon…