Career
Born in Cambridgeshire, England, Stonebridge began riding for the Matchless scrambles team in 1950, winning a gold medal in that year"s International Six Days Trial. In 1954, he joined the Bachelor of Scientific Agriculture factory team, helping develop the two-stroke, Bachelor of Scientific Agriculture Bantam scrambler. Stonebridge then moved to the Greeves racing team in 1957, becoming the company Competitions Manager and Development Engineer.
He competed in the 1959 F.I.M. 250cc European Motocross Championship, finishing the year in second place behind Rolf Tibblin.
Stonebridge died in October 1959 after a road traffic accident when he was a passenger in a car driven by his "boss" at the time, Bert Greeves.