Line of Duty star Martin Compston, who plays DS Steve Arnott in the BBC police drama, hails from Inverclyde and naturally speaks with a strong Scottish accent, so it's a testament to his vocal abilities that most viewers would never have thought he was anything other than a Londoner born and bred.
But as more people discover the truth, Compston worries they will begin to closely analyse his accent on the show.
“That’s one of the fears," Compston told Christine Lampard on ITV's Lorraine. "Because the bigger this [show] gets the more people figure out I’m Scottish and then the more they become accent detectives and they start listening."
During shooting, Compston reveals that he tries never to revert to his Scottish accent but says that because he filmed over a shorter period for the current fourth series, he may not have quite got into the London groove and is ready to apologise to viewers if his accent slips at any point.
"When I do the accent I tend to just stay in it," he said. "For me it’s like going to the gym, the more you’re in it the better you get. This year’s actually probably been the most difficult year[...] a lot of my filming was condensed so I had a lot more time off[...] so apologies if it slips at all.”
If you didn't already know Compston was Scottish we challenge you not to start listening for it next time you watch Line of Duty...
And for reference, here's an example...
Line of Duty is on Sunday at 9pm on BBC1