By Keily Oakes BBC News entertainment reporter

Harry Potter and the Goblet of Fire is the fourth movie adaptation of JK Rowling's phenomenally successful series.

Potter children: Then and now In pictures

It has been five years since a trio of unknown actors were cast as the junior wizards and witches Harry, Ron and Hermione.

Despite the latest film featuring a host of stellar actors including Ralph Fiennes, Michael Gambon, Alan Rickman and Dame Maggie Smith it is the young cast who are pushed into the limelight to publicise the film.

Daniel Radcliffe, Rupert Grint and Emma Watson have grown up on screen along with their characters, transforming into confident, laid back screen stars.

And Radcliffe, 16, Grint, 17, and Watson, 15, were able to take under their wing a new crop of young actors, including Katie Leung as Cho Chang and Stanislav Ianevsi as Victor Krum, many of whom were making their film debuts.

Speaking about his own experiences, Radcliffe said: "It's been an odd five years but it's been great.

"I've been through all the same stuff as Harry - like the hormones and everything. I've been doing it since I was 11, so it makes it easier in the long run."

Grint, Watson and Radcliffe have acted together for five years

Role model

Watson also says the job has become much easier as each film has passed.

"It felt like I didn't have to act at times. I know Hermione so well.

"There's so much of her in me, and me in her. It's been wonderful and I'm very fond of Hermione's character.

"She's turning into someone that people can identify with and she's a great role model."

The Goblet of Fire was a darker book from the previous three and the film follows in this vein.

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Because of the scarier contents the film has been given a 12A rating, meaning anyone under that age must be accompanied by an adult.

Watson said: "I'm in it and I was scared. I think it is much more of a thriller.

"It's always about staying faithful to the books and at the end of the day someone dies in the book, you can't avoid it."

Producer David Heyman said that at the test screenings it was the adults who were concerned their children would be scared rather than the children actually being too scared.

The Goblet of Fire sees Four Weddings and Funeral director Mike Newell take over the reins from predecessors Chris Columbus and Alfonso Cuaron.

He was reported to have said that the undisclosed multi-million pound budget was not enough to make the film the way he wanted.

But he said his quote was taken vastly out of context.

Newell said: "When I began the sheer scale of the film is daunting and then after a little bit, like every director and like every film I've made, big or small, you feel there isn't quite enough money to put the absolute bit of topspin on it.

"And of course you start to feel aggrieved that you have so little money - it's a monstrous nonsense."

Newell has declined to take on the fifth film, with producer Heyman admitting they are a "real endurance test".

A new crop of young actors has joined the regulars

'Wear a hat'

David Yates is the next director to take on the Potter franchise, with filming due to start in February.

Radcliffe, Grint and Watson signed on to reprise their roles for the fifth movie Order of the Phoenix but the possibility remains that they may not always play the roles.

Radcliffe said: "We are not absolutely confirmed as doing them all. We are confirmed to do the fifth but after that who knows."

The producers are in talks with Imelda Staunton to join the cast of the next film as Professor Umbridge, while secrecy surrounds other actors who may be joining.

Despite already appearing in three hugely successful films, Radcliffe insists the young cast are able to enjoy normal teenage lives although he added "it's often sensible to wear a hat!".

Radcliffe said: "I only feel famous about two days a year and that's the premieres, the films haven't cut into our lives that much.

"Having said that it's a possibility that may change once we turn 18 because perhaps the paparazzi and photographers have maybe been going easy on us, it might change but hopefully it will continue."