I do understand what the character is. More that I don't really get why it is used so often in British comedy shows. I thought it is probably traditional to have that character in sketch shows especially, and to show those comedians' renditions of a classic character.
I don't think "Spaced" has been mentioned yet. It was Simon Pegg's first big break ("Scotty" and the tech in Mission Impossible) and directed by Edgar Wright later known for "Shaun of the Dead" and "Scott Piligrim vs the World" . Also, try to track down "Rock Profile". It's the TV show Matt Lucas and David Walliams did before Little Britain. The Abba one, in particular, is brilliant and another example of drag in British comedy.
Miranda is fun. I personally really love the characters in Gavin and Stacey
British comedies are by far the best that I seen with clever scripts and writing. In HK, the comedies are just pure crap.
During my University days in the UK, Only Fools and Horses was by far the best comedy out there together with Blackadder. There was also clever writing in Fawlty Towers.