Gollum's precious moments: Andy Serkis' unexpected journey from The Lord of the Rings to The Hobbit

It's almost impossible to estimate the impact Gollum has had on Andy Serkis. Playing the wizened creature in Peter Jackson's Oscar-winning adaptation of JRR Tolkien's fantasy The Lord of the Rings was more than just another role. "It changed the course of my career," Serkis admits. Before Gollum, he was a respected British actor, gaining good notices for Mike Leigh films like Career Girls and Topsy-Turvy. Then along came Jackson. "That was a gift that came my way," he adds, looking very natty today in a brown and yellow check waistcoat. "I happened to be in the right place at the right time."

It is, you might say, the gift that keeps on giving. The 48-year-old Londoner is back this month as Gollum in The Hobbit, Jackson's long-awaited return to Middle- earth as he takes on Tolkien's 1937 children's classic, the book that pre-dates the events of Rings by 60 years. But this reprisal is just the icing on the cake for Serkis, who – in the wake of playing the character in Rings – became "a devotee of performance capture", the groundbreaking technology that allows an actor's movements and gestures to be recorded by computer and used to render a character digitally.

With Jackson and Weta, the Wellington-based special effects company responsible for creating Gollum, Serkis has been in the vanguard in this field (even if he's yet to gain an Oscar nod for his acting, much as he deserves it). His work on Rings led him to play the great ape in Jackson's 2005 King Kong remake before reuniting with him (this time Jackson as producer) on last year's Steven Spielberg-directed Tintin tale. Cast there as the bluff old boozer Captain Haddock, Serkis also went simian again, playing Caesar in Rupert Wyatt's hit prequel Rise of the Planet of the Apes.

Along the way, there have been live-action roles too – twice Bafta-nominated, for his chilling portrayal of murderer Ian Brady (Longford) and musician Ian Dury (Sex & Drugs & Rock & Roll), and a wonderful foil to David Bowie's mysterious Nikola Tesla in The Prestige. But it's as a champion of these new techniques where Serkis has made his mark. He calls it "fate", noting that before he became an actor, his visual arts degree at Lancaster University was in theatre, design and movement. "When I think about it, all of those things are my interests, and they've all been drawn together with performance capture."

He recently launched his own production company, The Imaginarium, an Ealing Studios-based outfit designed to use this technology, though reprising Gollum will doubtless shine the biggest spotlight on these pioneering methods. Arguably the most popular and most imitated character from Rings, with his whimpering cry of "my precious", Serkis admits it was an emotional reunion. "The Hobbit was one of the first biggish books I ever read. I remember vividly the 'riddles in the dark' passage, and it meant a lot to me to finally get to play it after all these years."

That sequence is Gollum's big scene in The Hobbit, where he plays a game of riddles with the book's title character Bilbo Baggins (played by Martin Freeman) as they tussle over the all-powerful "ring" he so covets. Serkis estimates this Gollum will be "different" from the one we saw in Rings. "Physically, he's not been scarred, he's not been tortured, he's not without his ring. But what you see in this scene is the moment of the ring being taken. You also see Bilbo sparing his life, where he could end it and thereby change the course of history for the entire Lord of the Rings trilogy."

Yet this only tells half the story for Serkis. Due to be in New Zealand for just two weeks to play Gollum, he wound up staying for the whole shoot after Jackson recruited him as the film's second unit director. It was an enormous responsibility for an actor who, despite all his on-set experience, had never ventured behind the camera. This wasn't any usual second unit either – filming the minor shots that the main crew doesn't have time for. It was everything from aerial shots to huge battles.

"Sometimes Pete gave me whole sequences to do, sometimes it was bits of sequences, sometimes it was finishing off scenes he hadn't finished. But it was epic." Ironically, Serkis had been gearing up to direct his first feature via The Imaginarium – but put it on hold when Jackson called. "Pete's known that I've wanted to direct feature films, and always been very supportive. When this came up, he said: 'I think you will get a great deal out of it. And we know each other well, you know Middle-earth and we'll be honest with each other.' So it seemed perfect timing in many ways. My first feature film was going to be an independent film and ended up being the hugest second unit possible… I've shot the equivalent of five independent movies."

For any budding film-maker, it's the opportunity of a lifetime – to work alongside Jackson and his co-writer/partner Fran Walsh close-up. "It was just like being given a Ferrari after just passing your test," smiles Serkis, fully aware of how fortunate he is. But, more importantly, it brought him closer to Jackson and Walsh. "Above all of the scale, the size, the popularity of the films, and all the rest of it, if they were making the smallest films in the world, I'd want to work with them because they are the most genuine film-makers I think I've come across."

It also meant Serkis got to see close-up the traumas that went on in pre-production, which was derailed numerous times – from a fire destroying sets to Jackson suffering from a perforated ulcer right before the shoot was due to start. Despite all this, "when Peter actually came to the first day of principal photography, he was remarkably calm". Serkis notes. On that first day, Jackson even staged a powhiri – the traditional Maori welcoming ceremony. "Once we'd got to that point it was a real sense of 'we're actually doing it, it's a real relief... It was really quite an emotional, beautiful start."

Emerging effectively as one of Jackson's most trusted lieutenants has taken Serkis, in a very roundabout way, back to his early days when he had designs on becoming a painter. This was soon sidelined for the stage, when Serkis became affiliated with London's Royal Court Theatre in the 1990s, playing the Fool in Max Stafford-Clark's version of King Lear and Potts in the original production of Jez Butterworth's Mojo, a role he reprised for the 1997 film. Also impressing in the 1997 Old Vic production of David Rabe's Hurlyburly, the role of the hyperkinetic Phil rather defined Serkis' early performances: frenetic, fast-paced, aggressive. "I enjoy high-speed about-turns in thought," he argues.

When I ask where he channels this aggression from, he turns back to his childhood. Born in Ruislip, he was chiefly raised by his mother, who taught handicapped children, as his father worked as a doctor in Iraq. "My relationship with my father was strange because he was living away for such a long time, so possibly it was born out of that. I suppose I naturally react… I'm quite contrary. If people agree on something, I tend to gravitate the other way by my nature. I don't like to be told what to do. I think it goes back to school. I like to do things I want to do and I really don't like doing what I don't want to do. I suppose you could liken it to that. I find it an easier emotion to access! I think I have a lot of internal energy, which does need to come out."

With four siblings, his memories from his early years would be regular holidays in the Middle East – far-flung place likes Tyre, Sidon, Damascus, Babylon and Baghdad. While he now lives in slightly less exotic North London, this thirst for absorbing other cultures, of moving out of a comfort zone even if only for a while, stayed with him. Before he made King Kong, he spent weeks in Rwanda observing a group of 23 mountain gorillas in the Virunga volcanoes, joining a research party from the Dian Fossey fund that was studying testosterone in the males.

Making The Hobbit was different, though. Having spent seven of his past 12 birthdays in New Zealand, this time it meant being away for almost a year from his actress wife Lorraine Ashbourne – they've been married since 2002 – and their three children. "That was hard. That was unquestionably very, very difficult," he says. He's clutching at his gold wedding band now – his own "precious ring", he jokes – but being so far away for so long was painful. "We used Skype a lot. Thank God for Skype!" he chuckles. "Since Lord of the Rings, Skype has singularly been the most important technological advancement in film!"

As a result of working on The Hobbit (which will be released in three parts), "this has been the longest break I've ever had from acting" says Serkis, now juggling three projects as director (two performance capture, one live action) for his company. But with the Jackson-directed Tintin sequel in the works and next year's follow-up Dawn of the Planet of the Apes to shoot, Serkis plans to be back on our screens soon (even if his face isn't). "I love acting and certainly won't give it up," he says, "but it's part of a bigger canvas for me now." The possibilities must seem endless.

'The Hobbit: An Unexpected Journey' opens on 13 December

This article appears in tomorrow's edition of The Independent's Radar Magazine