Although what Nanner said is right, it's not always the case. We have some real dog shit comedy shows on here that seem to go on forever (My Family & My Hero for instance) that the BBc seem to love..as well as the old folk I guess.
To be honest most of British TV is pretty shit with a few exceptions in the Drama department. All the best shows are from the other side of the pond. Lost, Battlestar, Heroes, Prison Break, Nip Tuck (My missus' fave)