GTA V: London?
No.
You'd get away with murder, literally, as the police are very rarely found wandering the streets and secondly, as someone else said, UK police get pointy sticks in place of guns. Modern London gangsters would be a nice twist but to be fair it wouldn't be too difficult to have a Cockney gangster who happens to live in sunny San Andreas and give him all the cliche stories and quotes.
I know we've been over this, but I'd quite like to see GTA V: Wild West, where in place of cars we were given horses, and instead of drug cartels we had highwaymen and moonshiners, and in place of rocket launches and uzis we have Wild West themed guns... and hey, instead of prostitutes we could have, um, prostitutes. /sarcasm