Specialising in comedy writing, he worked with several figures at the forefront of British comedy, such as Tommy Cooper, Peter Sellers, Dick Emery and Mike and Bernie Winters.
He had several screenwriting projects with film director Val Guest whom he first encountered as an actor in 1948.
Following his discharge, John pursued a career in films but only served in minor roles.
He did however make many contacts and moved into scriptwriting in the late 50s, having considerably more success in this field.
His need to choose a new name stemmed from the pre-existence of the actor Jack Warner who was operating out of the same studios.