His first major comedy role was in "The Lavender Hill Mob" (1951): with Alfie Bass, he made up the bullion robbery gang headed by Alec Guinness and Stanley Holloway. He also appeared in "Lady Godiva Rides Again" and "The Galloping Major", both films were released in 1951, and as Harry Hawkins in "The Titfield Thunderbolt" (1953), and also had a lead role in "The Wedding of Lilli Marlene". He featured in another Alec Guinness film, "Father Brown" (US: "The Detective", 1954) and in "Trapeze" (1956) as Harry the snake charmer, a circus film which was one of the most successful films of its year, and he played Master Henry in "Outlaw Money" (also 1956), an episode of "The Adventures of Robin Hood". James had a supporting part as a TV advertisement producer in Charlie Chaplin's "A King in New York", a non-comic supporting role as a journalist in the science-fiction film "Quatermass 2", and he performed in "Hell Drivers" (all 1957), a film with Stanley Baker. The next year, James starred with Miriam Karlin in "East End, West End" by Wolf Mankowitz, a half-hour comedy series for the ITV company Associated Rediffusion. Set within the Jewish community of London's East End, the series of six episodes was transmitted in February and March 1958, but plans for further episodes were abandoned after a disappointing response. For a while though, it had looked as if his commitment elsewhere might end his work with Tony Hancock, one of the most popular television comedians of the time.