It wasn’t only Londoners born near a certain church in Cheapside who grimaced when Dick Van Dyke’s chimney sweep, Bert, opened his mouth in the 1964 musical, Mary Poppins, an offence for which he apologised more than half a century later.
But if Van Dyke murdered the cockney accent, it seems Londoners, and southerners more broadly, are among the worst at spotting people mimicking their accents, with northerners, Scots and the Irish performing better.