Right now, for me, some of the funniest lines in any British production are being delivered by Gary Oldman in Slow Horses. It isn't a comedy but he has given his character all of the depth it has in the books and as a depiction of how people use humour to deal with stress it has no equal.
Other than that, my all time award goes to the minstrel in Monty P and the Holy Grail. His songs are hilarious because they're packed with inconvenient truths, reframed to make them heroic, as in the immortal verse, 'Yes, brave Sir Robin turned about, and valiantly he chickened out.' That and the Holy Hand Grenade of Antioch.
I'd add in Good Omens, which stars David Tennant and Michael Sheen as an angel and a devil who form an unlikely alliance. Terry Pratchett's influence is everywhere and it is as funny as anything he wrote. Particularly the terrier of doom. There are some inspired moments.
