Well, I understand British culture to some degree, as I really like what you guys have over there. Like for example, trucks are lorry, an apartment is a flat, and an elevator is a lift. So yeah, I know a few things.
As for the context, they're in downtown London in the year 2027, so about 17 years hence. However, I figured that a lot of modern day words and sayings would still be applicable even then. Mr. Carter is a spy, one of those back alley shady characters who slink around steal secrets. The other guy is the president of the Bank of England. He's a businessman at heart, but he also funds lots of black organizations with less than respectable (ie, world domination) goals in mind. (I'm not trying to say that all bankers are evil, but this one just happens to be. lol)
I hope that helps a little.