many great ones, but the funniest Britcom I ever saw was The Fall and Rise of Reginald Perrin (watch it in order of the episodes, as the story line develops in sequence)
mentioned numerous times...This may be the show i look on dvd netflix and rent.
The best episode is where that actor of genius Geoffrey Palmer, the only man who can make you laugh by acting as a complete deadpan bore, tries to enlist Reggie into his secret conspiracy to take power in a coup (not so fanciful in 1970s Britain) and Reggie’s response about about the rear admirals and the queer admirals, look it up on YouTube.