717 CRE is the Swallow Doretti which was used by the factory to promote the marque and during the 1954 season Don Truman drove the car for the factory race team. At this time, Don who personally owned a Triumph TR2 stated that, "the Doretti was a much superior car in suspension and usable performance."
Don had two races at Silverstone, both 100 milers, and his only brief was to beat the Austin Healeys, which he did - much to the delight of Eric Sanders, Swallow's managing director. Unfortunately after these two races the works decided give up official racing - which was a pity. In September 1959, Don Truman (1922-2011) retired from racing but maintained his involvement with the sport for many years.
Bill Piggott in "Triumph by Name Triumph by Nature" comments that he'd heard that one of the very earliest Triumph TR2 engines (maybe TS-1E) was fitted to the prototype Swallow Doretti. According to the 1965 vehicle continuation logbook, Engine No.TS-1E was installed in Chassis No.100-RH that was first registered as 717 CRE on 8th May 1954.