Despite his later self-reinvention as a florid-faced Daily Mail columnist of the 'We're all going to hell in a handcart' variety, he'll be best remembered for his earlier work, especially the screenplay for Whistle Down The Wind in which Alan Bates plays an escaped murderer hiding in a barn, mistaken for Christ by some local children (best line: 'He's not Jesus, he's just a feller!'), and of course for the immortal Billy Liar.
Confession time: I played the title role in a best-forgotten amateur production in Manchester in the early Eighties. I think the reason I got the part was that the only other person in the cast of the right age was an ex-public schoolboy whose attempt at a Yorkshire accent was even more execrable than mine. Tom Courtenay and Julie Christie did a rather better job: