Really? I had no idea he had a british accent in CV, guess I never really paid attention to it...British Villians rule!
Being a Brit myself, I have good faith that Wesker's accent is British in CVX and RE4.His accent in RE5 sounds forced, as he sounds American when he says some lines ("You haven't changed"), but I reckon that Douglas was trying to be as British as he could.
I think they should make it sound slightly american and sinister, like CVX, RE0, RE4 & Wesker's Report.