The show stars Ronnie Barker as Norman Stanley Fletcher ("Fletch"), described by his sentencing judge as an 'habitual criminal', Richard Beckinsale as Lennie Godber, Fletch's surprisingly innocent cellmate, Fulton Mackay as Mr McKay, a tough warder, and Brian Wilde as Mr Barraclough, a timid warder. It featured a number of other prisoners, such as Blanco (David Jason), Samson and Delilah (a gay couple), Grouty (a gangster who unofficially runs the prison), etc.
It led to a TV sequel entitled Going Straight (1978) and a film version (1979). Richard Beckinsale died at the age of 31 shortly after completing the film.
The script allowed the prisoners to swear without offending viewers by using the word naff. It was used in place of another well-known four-letter word, in phrases such as "Naff off!". Ronnie Barker claims he invented the word but there is evidence that he may have borrowed the word from Polari or from Australian slang ("Nasty as fuck"). A genuine neologism was the word nerk, which was used in place of the more offensive word berk (Cockney rhyming slang, short for "Berkshire Hunt").