Sopwith took up motor racing and formed his own team, Equipe Endeavour, named after his father's racing yacht.[1] His success as a racing driver saw him win the first-ever round of the British Saloon Car Championship in 1958. That year he narrowly lost out on the driver's title to Jack Sears after a ten lap shoot-out at the end of the season, after the two drivers finished on equal points.[2] In 1961 he switched from car to powerboat racing. In 1961 He won the first ever Cowes - Torquay race in Thundebolt, following up with wins in 1968 (Telstar) and 1970 (Miss Enfield II). In 1965 he won the Cornish "100" Offshore Class 3, powerboat race in a boat called 'Thunderflash', just beating Mike Beard in 'Mongaso'.[3]
He was the owner of Endeavour Holdings Limited, a car dealership in Portslade, Brighton, with a turnover of £17 million.[when?]