Not "great movies" by any means, but I really enjoy the modern lowish-budget British black comedies that the likes of Film4 have funded. They have a unique feel to them. Examples that spring to mind are
Shallow Grave, Severance Attack the Block etc.
All else apart, they're a nice antidote to the US impression of Britain as portrayed in
Mr Bean and
Love Actually
Ps - Whilst googling for the name of
Severance I found out that
Seven Psychopaths is categorised as a 'British film' too. I had no idea. Quality film that.