DC's vertigo line certainly attracted some of the big British born comic authors, Neil Gaiman with The Sandman and Alan Moore withV for Vendetta
Moore created John Constantine during his run on Swamp Thing, Constantine was later spun off to his own series Hellblazer
other British born creators i like are Grant Morrison, Jamie Delano and Peter Milligan
Morrison had a great run with lesser known character Animal Man and a glorious stint on Doom Patrol, he also wrote one of my favourite Vertigo one shots Kill Your Boyfriend
Delano wrote the first 40 issues of Hellblazer, setting the tone for the comic starring Moore's creation John Constantine
Milligan revived a lesser known DC character Shade, the Changing Man and also wrote my second favourite Vertigo one shot The Eaters