by LAURA ROBERTS

Last updated at 11:50 29 June 2007

They may be heading back to Hogwarts again, but Harry Potter and his friends look to be outgrowing their schooldays.

Daniel Radcliffe, who plays the boy wizard, lined up with his co-star Emma Watson for launch of the fifth film in series.

But the cheeky grins and childish looks of seven years ago, when they were first cast for the roles, have been magicked away. In their place are the smiles of those on the brink of adulthood.

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However, the pair will need all their knowledge and experience to deal with the challenges of Harry Potter and the Order of the Phoenix, based on the book by JK Rowling.

Not only will Harry and Hermoine Granger, played by Miss Watson, face terrifying battles in the £75million film, but Harry will also experience his first proper kiss.

Radcliffe, 17, who has left school and recently stripped off to play a deranged teenager in the play Equus, admitted at the launch that the latest film was his "most challenging Potter role yet".

It took 30 takes to perfect the kiss with his onscreen girlfriend Cho Chang, played by Glaswegian actress Katie Leung.

He added, however: "Kissing Katie was a very comfortable experience, compared to being naked on stage.

As the boy wizard teeters on the edge of manhood, his fans will have to grow up too.

Some of the previous films have been rated PG, for Parental Guidance, which means unaccompanied children may watch.

But the latest is a 12A, meaning anyone under 12 needs an adult's permission to watch.