That September he won his first race, the National Cyclists' Union junior medal competition at Paddington, central London.

[5] Peacock rejoined Kingston Road Club and rode the 1951 national sprint championship, where he was beaten in the quarterfinal by Lloyd Binch of Nottingham.

"[5] In 1952, by then a member of the Tooting Bicycle Club in south London and on 5 July won the British sprint championship, at Herne Hill velodrome.

That brought selection for Britain in the Olympic Games in Helsinki; he came fourth of 27 behind Enzo Sacchi of Italy, Lionel Cox of Australia and Werner Putzenheim of Germany.

He represented England and won a gold medal in the Track 1000m Match Sprint at the 1954 British Empire and Commonwealth Games in Vancouver, Canada.