“Its odd that Harry Potter is exposure, for want of a better word, “ says Harry Melling, “because there has been so much life since then and other adventures I have had.”

It is 15 years since the Mill Hill-born actor first appeared on our screens as Dudley Dursley, a role he played from ages ten to 19 and not only has he transformed physically but, unlike the famous trio, he has made the stage his focus.

Harry went on to train at the prestigious London Academy of Music and Dramatic Art (Lamda), has appeared at the National Theatre, Barbican, Trafalgar Studios and Southwark Playhouse and is now preparing to take to the West End stage in Hand to God, which opens on Friday.

The show, which was a smash hit on Broadway, is an irreverent human and puppet comedy set in a devoutly religious Texan town.

“In terms of acting this is like nothing I have done before," explains the 26-year- old who plays shy teenager Jason who finds his puppet Tyrone seemingly possessed by the devil and leading his friends into sin.

“It’s a very different acting challenge that to be honest scared me senseless to begin with as I had no idea how to do it. It’s been the biggest challenge of my acting career so far.”

Although Harry started out with a role in the second highest grossing film series in the world, he seemed destined for a life of drama long before then.

“I come from a quite hideous dynasty of actors, there’s loads of us," says Harry who is the grandson of former Doctor Who Patrick Troughton and nephew of respected actors David and Michael Troughton.

“Hideous meant in the nicest way, " he laughs. “I fell in love with theatre watching my uncle David in The Tempest at the RSC when I was very young, so young I had to be in the director’s box.

“I fell in love with the idea that people were up there telling these stories and the magic of it and sort of knew then that I wanted to do it.”

The former pupil of St Paul’s C of E Primary School on The Ridgeway landed the role in Harry Potter after his mother Joanna Troughton sent his photograph to casting directors and says working on the films definitely taught him a lot.

“Working with Richard (the late Richard Griffiths) and Fiona (Shaw) was amazing, The way they worked, and think, their wit, intellect and sense of fun are all things that hopefully through osmosis have gone into me somewhere.”

But Harry emphasises several times during our chat that Harry Potter was a ‘long time ago’ and it’s clear he is keen to shake off the mantle of fame the films bring.

“I haven’t really thought about that, “ he says about being in the spotlight.

“I try not to because I don’t really care for it. I just want to do the play and what Rob has written justice. In terms of profile I don’t think of that because its not my job.”

The films did more than just make him a name, he used his earnings to transfer from Hendon School to attend the fee-paying Mill Hill School, a move that helped further his drama training.

“It’s really hard to talk about because I wasn’t having such a good time there.

“I terms of state and private education I couldn’t care less but there were things I wanted to do in terms of drama that weren’t facilitated. So I sent myself off to Mill Hill school up the road when I was 15 and paid the fees. “My parents couldn’t afford it but luckily Harry Potter allowed me to go there.”

He also became a member of the National Youth Theatre, but says it was getting into Lamda that changed everything.

“I guess you have to start again after Harry Potter because it is such a huge franchise so where do you go after that? What sort of actor do you want to become? One that goes from franchise to franchise trying to make as much money as possible? That’s not what I wanted. I wanted to act and I have always loved the theatre.”

He left Lamda early to appear in Mother Courage and her Children at the National Theatre, once again playing Fiona Shaw’s son, and last year wrote and performed Peddling at the Arcola.

More recently he was in Belfast filming Hollywood action adventure Lost City of Z.

“I play this young National Geographic type person who grows up during the film, he starts out quite pompous and changes.

“The director and actors were great. Sienna Miller is lovely, Rob Pattison is lovely and Charlie Hunman, they were all just such lovely people.”

Harry was in Prague filming an episode for the third series of BBC drama The Musketeers when the call came for the Hand to God audition.

St Albans & Harpenden Review:

“I remember everyone in the States at the time talking about it. It’s so outrageous in its wildness that it almost shouldn’t be within the politeness of theatre. It’s not like anything I’d read before and can’t be pigeon-holed.”

Rehearsals began in early January and mastering the intricacies of puppetry have been a real challenge for Harry, who now lives in Leytonstone and loves the colour of east London.

“Every second I’m not in rehearsals I’ve been hanging out with Tyrone. He has sort of lived with me for the last month.

“It’s amazing how you begin to think like him and you can isolate two parts of yourself and your thoughts. You are fundamentally talking to your hand and you have to make that thing breath life, that’s been the challenge of the play.

Harry says he can identify with both the shy teenager he plays who is dealing with his father's death and trying to figure out who he is, and the wicked Tyrone who stirs up trouble.

“We have all been in those situations where we can’t quite choose our words correctly to illustrate what’s going on and equally have been that person who has gone with the flow and done whatever he wanted to do in that moment. The great parts explore those extremes.

“Whether Tyrone is psychologically the devil on his shoulder or literally that supernatural thing, that is for the audience to decide. That is beautifully ambiguous.”

Hand to God plays at Vaudeville Theatre, The Strand, WC2R 0NH from February 5 to June 11. Details: handtogod.co.uk

Read our review of Hand to God here.