Divided by the R.

One of the most noticeable differences between American and British RP pronunciation is the way we treat the letter ‘r.’ Americans mostly pronounce it wherever it appears in a word, whereas we Brits only pronounce it when it precedes a vowel. Anywhere else the ‘r’ merely extends the sound of the previous syllable. And that’s why the only time Gregory House’s accent grated with me was when he called a member of his team ‘thirteen.’ As a British actor expertly faking an American accent, his pronunciation of thirteen was the one time when I felt he overstated the difference.