Charlie and Harry are at university now studying law and business. They’re preparing to join the workforce, but you probably know them as the toddlers in one of the most viewed videos of all time.

‘When they were young, I was kind of cool to them, I think, because their friends would join in with the songs,’ he said. ‘But now it’s just, “Shut up, Dad! Go away! Close the door.” They weren’t even ...