11. Fawlty Towers
The most stunning fact about Fawlty Towers is that only twelve episodes were ever made. Just a dozen, half-hour instalments, but due to the nature of the show, created by John Cleese and his then wife Connie Booth, it feels like there are considerably more.
Each one is a nugget of pure comic brilliance, stuffed with more jokes than you could hope to laugh at in one go; it's slapstick at its very best, but there are varying levels of humour and so much interplay between the characters that you can never tire of watching them in action. The iconic moments - such as the goose step and the car-thrashing - never lose any of their lustre, and there are countless smaller details that might've passed you by the first time around.
They chose to stop at 12 because they couldn't top them. They were right then, and it's arguable that no other British sitcom has managed to since.