(foaled 1936), English racehorse (Thoroughbred), unbeaten during the 1939 racing season when he won two of the events comprising the British Triple Crown: the Two Thousand Guineas at Newmarket and the Derby at Epsom Downs. The beginning of World War II deprived him of the chance to race in the Saint Leger, the last of the Triple Crown events, at Doncaster. Foaled by Fancy Free and sired by Fairway, Blue Peter was bred and owned by Lord Rosebery and trained by Jack Jarvis. He raced only twice in 1938, but in 1939 he was unbeaten in four races. Blue Peter sired Ocean Swell, the 1944 Derby winner.