John formed the improvisational theatre duo, "Sal's Meat Market," in which he co-wrote, directed, and starred. After the first year, "Sal's Meat Market" performed to standing room only crowds throughout Europe. During these years, John became a master at integrating mime, dance, song and improv in 634 performances. Tight theatre schedules and good training shaped John's talent into the master improvisational acting for which he is famous. The British Arts Council awarded John and his partner a full grant to tour clubs and theatres throughout Europe, recognizing his comic talent from 1973 to 1978.

London's Evening Standard wrote, "the current show demands at least 20 characters...in fact, they are all two men...they are like two musicians who skid around at great speed to give the impression that a full orchestra is playing. It's done with incisive timing and a hard-edged wit that stops short only this side of hysteria."

To this day, John's comedy troupe is the only American group to have received a grant from the British Arts Council.

In between his theatre touring in Europe, John was a producer and screenwriter for the BBC, Paravision, Royal Court Theater, Hampstead Theater Club, Royal Academy of Dramatic Arts, and Granada TV. Projects he penned include: 5 Minutes in America, The Golden Dreamboat, Friends in Space, Crown Court and Winner Take All.

On the silver screen, John's first motion picture role was in the Golden Globe nominated The Ritz (1976), directed by Richard Lester and starring Rita Moreno and Jack Weston.

During this time in England, John appeared in over 22 major motion pictures making him not just a movie star, but also an actor to be reckoned with. His credits also include Gandhi (1982) and Star Wars' Empire Strikes Back (1980). Additionally, he starred in the Granada TV series, Small World.

His unparalleled professionalism has been described as, "John seemed to always have tremendous ease in front of the camera. This is part of his film prowess, too."