Harry Potter Stars 'Remain Grounded'

Daniel Radcliffe, Rupert Grint and Emma Watson remain grounded - despite the global success of the Harry Potter movies.

David Heyman - who produces the films based on the books by J.K. Rowling - insists the the trio haven't been allowed to become divas since they made the first money-spinning film back in 1997.

Speaking at the premiere of his new movie - the Jim Carrey-starring Yes Man - Heyman said, "On the Harry Potter set we have a lot of crew from the first film.

"You can't get away with anything there, you get joshed and played with. You can't have any airs or graces.

"You cast for the moment, you have no sense of how someone is going to survive or how they're going to develop. I've been very fortunate with the kids. There are so many cases of young kids being damaged by the experience or going off the rails and fortunately with Dan, Rupert and Emma that hasn't happened to them... yet!

"I don't think it's going to happen to them, they're pretty together, really good kids, well - young adults now."

David revealed work is about to begin in the new year on the seventh movie in the series: "We finished the sixth film which'll be coming out next summer and we start filming the seventh which we'll be breaking into two parts for a 54 week shoot starting in February."