The straighter he played it, the funnier he became.
Who else can do that??
The speech he makes to Leonard Rossiter in Series Two of The Fall and Rise of Reginald Perrin about who his secret army will be against is one of television's best ever comedy moments.
He will be remembered for Reggie Perrin, Butterflies, Fawlty Towers, Fairly Secret Army, Executive Stress, As Time Goes By and Blackadder Goes Forth.
A legend.