Martin Freeman, Benedict Cumberbatch and the British TV stars in Peter Jackson's The Hobbit

Best known as Spooks’ Lucas North, Armitage was preparing to shoot Sky1’s Strike Back... “I got a call saying, ‘Could you just hold off from that job?’ To be honest, nothing would have stopped me from doing Thorin. If I never do another piece of work again after this, I think I’ll be happy, genuinely happy.”

James Nesbitt – Bofur

Nesbitt has never been short of offers since Cold Feet but the actor couldn’t resist the lure of The Hobbit, and moved his wife and two daughters to New Zealand for a year. “Being part of the film was an adventure for my entire family. The girls got to have fun around the studios.”

Ken Stott – Balin

Edinburgh-born Stott, best known for playing detectives (BBC’s Messiah serials and ITV’s The Vice), says, “I often sat there thinking I looked daft but there was always another dwarf looking just as daft round the corner. Remaining upright under the weight of the costumes was the main challenge.”

Barry Humphries – The Great Goblin

Having created Dame Edna Everage and slovenly Sir Les Patterson, the 78-year-old comic adds another imposing creation to his CV: the CGI-enhanced Great Goblin. “I’m not exactly Hugh Grant. I specialise in grotesquery,” says Humphries.

Benedict Cumberbatch – Smaug

Not content with playing the villain in the next Star Trek film, the Sherlock actor will voice and physicalise The Hobbit’s malevolent dragon. “I think my eye will open at the end of the first film, then you’ll get the rest of me in the second,” he says.

Martin Freeman – Bilbo Baggins

Benedict’s Sherlock co-star Martin Freeman has gone from playing faithful companion Dr Watson to a role in “the biggest film I’ll ever do”. How does he feel about taking on the lead role in a Peter Jackson film? “I’m very hopeful, but also nervous because I want to please myself first of all, and I also hope everyone else likes it.”

Sylvester McCoy – Radagast

The seventh Doctor Who draws parallels between the Doc and his new role: “The Doctor is a wizard and Radagast is another,” he says. “Peter Jackson has my costume from when I was Doctor Who [he reportedly bought it on eBay] and now he has my Radagast one.”

Aidan Turner - Kili

The star of Being Human swapped the guise of a vampire for the role of a dwarf - for 18 months. His reaction to the news he'd got the part? "Yes! Yes! Oh Yes!"Read his interview with Radio Times here.

The Hobbit: An Unexpected Journey is released in cinemas nationwide on Thursday 13 December. Read our review here.