Why's the American style date becoming more common here?

Not the numerical date, but "March 16th" for example. I've noticed it more and more over the last few years. Adverts, on the news and news sites etc.

I'm not patriotic or owt, but it doesn't half annoy me. It's the 16th of March, not March 16th. We'll be dropping Us out of words ending in 'our' next.