Famous for its use of "Mockney", which sounded like Cockney slang, but was made up by either George Cole or the scriptwriters. Some expressions became so well-known they have since passed into the language, including "A nice little earner" (a profitable task), "'er indoors" (the wife), "give him a little slap" (beat him up).
In the opening titles for the Terry McCann episodes (Seasons 1-7) a sporty white Ford Escort with a blue stripe down the side is seen in the background. In a close-up shot of Terry looking at the Ford Capri he is about to buy, the Escort's window is up, but in a later shot where Arthur and Terry walk from the back of the Capri to admire it from a distance, the Escort's window is wound down.
The title sequence originally had 'Euston Films presents' over the opening shot. Later prints of the same episodes did not have this. (Additionally, early episodes also began with the Thames Television ident sequence, which, particularly after Thames lost their broadcast franchise in 1992, have been dropped from most repeat runs).