James and Oliver as the Weasley twins in their magic shop in the 2009 film Harry Potter And The Half Blood Prince

The Magic shop: James and Oliver as the Weasley twins in their magic shop in the 2009 film Harry Potter And The Half Blood Prince

‘Michael Gambon was just one of the best role models we could have hoped for,’ says James, ‘one day, he was filming the scene where his character Dumbledore dies, so it was quite an important day for him.
‘He asked me what I was doing at the weekend and I happened to be recording Peter and the Wolf. He could easily have said: “Great, well have fun!”, but he asked me for the script and took ten minutes out to write down some pointers.’
Similarly, Julie Walters who played their mother Molly Weasley was, ‘pretty cool’, says Oliver, ‘and we could always go to her for advice. We were going to do something in Manchester and needed help with our accents. She wrote down all the voice coaches she could think of. She made a big effort for us.’
They remain good friends with their ‘younger brother’ Rupert Grint. Oliver says: ‘We have the same sense of humour and he’s just the coolest person — I’ve yet to meet anyone who says a bad word against him.
‘He had the best dressing room, so that was our unofficial Green Room and last year he called up asking if I wanted to go to Wimbledon. He got us into the Royal Box and I was saying: “Mate, this has ruined me for anything else”.’
They’ve also kept in touch with Harry Potter himself, Daniel Radcliffe. ‘We were in New York last year and saw him on stage in How To Succeed In Business Without Really Trying. He knew all the cool places to go, especially this one place where it was three knocks to get in and then there was this really huge restaurant inside, so we were sitting there with Kevin Spacey about three tables behind us.

Pranksters: James and Oliver battle with broomsticks at the opening of Harry Potter: The Exhibition at the Powerhouse Museum in Sydney, Australia, in 2011

‘We haven’t seen much of Robert Pattinson [who played Cedric Diggory], but he was a top guy who wanted to have a good time and because it was before the whole Twilight thing, there weren’t always a load of screaming girls whenever we went out.’
And they haven’t seen Emma Watson recently either, she’s  in LA filming the latest Sofia Coppola film, The Bling Ring. ‘But she was great,’ says Oliver, ‘and she beat me at table tennis.’
Typically for brothers, Oliver and James have a competitive streak. ‘Whether we’re playing golf, PlayStation, or we’re on Twitter,’ says James, ‘and yes, I know that he’s got more followers than me because I was off it for a month or two,’ he grins.
Would they both go up for the same roles? ‘Yes,’ says James, ‘We decided we should go for the same parts. If I don’t get it, then I’d much rather Oliver got it than someone I don’t know.’