You know, I played in a clan that was nearly half Europeans, and half of them were British, and I've got the say, the Brits are pretty talkative, minding that there are rules like "treat all gamers with respect."
Anyhow, the argument by the people posting in this thread seems to be that they don't talk because of the trouble they receive in terms of their accent. So here's some helpful pointers to help Brits get through the rough times:
1) Try a new accent. Obviously, doing an American one would be best, but if you can't do that, here's a list of countries known for speaking a form of English whose asses Americans don't believe they saved in WWII:
Canada
South Africa
Australia
Ireland
New Zealand
You could also try doing another European accent, as though you were from a non-English speaking country but could speak English (***WARNING*** DO NOT use French or German. You think you've got it bad? We actually DID save the French's ass in WWII, plus we equate Germans with Nazis, and we beat them. Other countries to consider avoiding are: Ethnically Slavic countries, like Russia and Ukraine, where you'll be considered a Russian, and thus a dirty commie, or Spain, where you'll sound vaguely Mexican)
2) Failing a complete change of accent, why not try to emulate American gaming speech patterns? This is very simple: Every time you say something, put down a minority group. For gamers, gays and blacks are the primary targets, but don't forget to work the Mexican and Asian angle. And if you're playing a military game, you can probably get away with bashing liberals (or, for bonus points, famous black liberals, like Obama or Al Sharpton. Triple score if you claim Obama is also gay). This way, Americans will know that while you have a strange accent, you share their rabidly offensive ideology.
3) Don't play with Americans. Sometimes you just have to throw in the towel and accept that the US often ruins everything. We put Disney World in Paris. I mean, it's f***ing Paris. The two most commonly known words worldwide? "Okay" and "Coca-Cola." Yah, that's right, the second most well known word is an American brand name. We did that. When you reach that point where you've given up trying, you'll have to take advantage of the few games that allow you to play with your friends, and not with just random strangers.
I hope this helps out my fellow gamers on the other, less American, side of the Atlantic.