I am an American, New York-born, but I started to spend time in London in the 1990s, teaching classes to international students. Being interested in language, and reading a lot of newspapers there – one of the courses I taught was on the British press – I naturally started picking up on the many previously unfamiliar (to me) British words and expressions, and differences between British and American terminology.
Then a strange thing happened. Back home in the United States, I noticed writers, journalists and ordinary people starting to use British terms I had encountered. I’ll give one example that sticks in my mind because it is tied to a specific news event, and hence easily dated.
In 2003, it became clear that the US would invade Iraq. Months passed; we did not invade. Then we did. Journalists faced a question: what should we call that preliminary period? In September 2003, the New York Times’ Thomas Friedman chose a Britishism, referring to “how France behaved in the run-up to the Iraq war”.
Run-up, previously unfamiliar in the US, quickly began to be very widely used. I know because of the app Google Books Ngram Viewer, the online tool that can measure the relative frequency with which a word or phrase appears in the vast corpus of books and periodicals digitised by Google Books (including separating out British and American use). Ngram Viewer shows that between 2000 and 2005, American use of “the run-up to” increased by 50%.