Grant trained as an actor at the Royal Academy of Dramatic Art working in his spare time as a frozen food salesman and also coincidentally in view of his later career as a bus driver After doing national service in the Royal Artillery he made his stage debut in 1952 as Sydney in Worms Eye View at the Court Royal Horsham In 1954 he married Jean Hyett the marriage would end in divorce Grants first London appearance was in The Good Soldier Schweik at the Duke of Yorks Theatre in 1956 and he spent several years at the Theatre Royal Stratford East before getting the lead role in the musical Blitz at the Adelphi Theatre in the West End for two years In 1962 he married for the second time to Christine Sally Kemp they later divorced In 1964 he appeared at the Piccadilly Theatre in Instant Marriage a musical farce for which he wrote the book and lyrics with music by Laurie Holloway He had by now started to make film appearances including Sparrows Cant Sing 1963 the screen version of a play written by his future On the Buses costar Stephen Lewis in which he had previously acted on stage and the film version of Till Death Us Do Part 1969 He returned to the Theatre Royal Stratford in 1967 and starred in the satirical play Mrs Wilsons Diary as George Brown the Foreign Secretary in Harold Wilsons Labour government this play later transferred to the West End When the reallife Brown resigned in 1968 Grant was so concerned that his unflattering portrayal of him as a drunk may have contributed to his resignation that he offered to stand down from the part but reluctantly continued