So the irritation is mutual! We’ve reported several times on Americanisms in British English in this blog, but if you want to read on the increase of British expressions in American English (toff, cheers, brilliant, loo), take a look at this article in the online New York Times: Americans are barmy over Britishism.
With thanks to Bob Ackerman (an American in the UK), as usual.
Bridging the Unbridgeable 
My American friend living in the UK posted the link on my Facebook wall. I love the fact that the two Englishes are not drifting apart so much as some people say they are. In your face, Noah Webster!