His wife, the Duchess of Cambridge, will not be present as she continues to recover following a bout of severe pregnancy sickness.
For those not familiar with JRR Tolkien's The Hobbit, it is set some 60 years before The Lord of the Rings and centres on Bilbo Baggins (played by Martin Freeman).
In the story, Bilbo tries to reclaim the lost Dwarf Kingdom of Erebor from a dragon named Smaug as part of a clan of 13 dwarves.
Their journey takes them through lands swarming with Goblins and Orcs, deadly Wargs, Sorcerers and Gollum and his 'precious' ring.
The UK premiere is a little under two hours away and soon director Peter Jackson and the cast will be greeting fans.
Filming of The Hobbit: An Unexpected Journey started in New Zealand in March 2011. Filming finished in July.
Jackson chose to shoot the film at 48 frames per second rather than the industry standard of 24 to make the special effects and landscape shots look smoother.
The films enjoyed its world premiere in Wellington, New Zealand, on November 28. It was reported that 100,000 people turned up to watch the stars of the film arrive.
Air New Zealand, the country's national airline, released a Middle Earth-themed onboard safety video which proved to be something of an online hit.
The film has received mixed reviews from and while most critics concede that it is visually stunning, a recurring gripe seems to be that, at two hours and 49 minutes, the film is overly long.
That there is Dominic Monaghan - one of the stars of The Lord of the Rings trilogy - looking dapper ahead of his appearance at tonight's showpiece.
Damon Smith, a film critic from the Press Association, awarded the film a rating of six out of 10.
Smith wrote: "Visually stunning flashbacks, which fail to advance the plot, are roughly hewn into a sprawling narrative that doesn't kick into second gear for a good 45 minutes."
He went on to write: "The decision to shoot the film in 3D at the higher rate of 48 frames per second compared to the usual 24 frames will divide audiences."
Martin Freeman has told Sky News that The Hobbit is likely to be the biggest film he is ever involved in.
He quipped "sexual" when asked what it was like to wear hobbit feet.
Cate Blanchett says she is "cold, but very excited" to be at the premiere.
Blanchett went on to say: "It was relief to put the [elf] ears back on."
More from Damon Smith: "Everything looks cleaner and crisper - you can see the stitching on Gandalf's hat and prosthetics in minute detail - but this might be too much heightened reality for a sweeping fantasy that romanticises the bonds of trust between gung-ho brothers."
One hour to go before the film gets underway.
When asked if he was nervous about playing Bilbo Baggins, Martin Freeman said: "No, I had no nerves about taking the part because I knew Pete [Jackson] really wanted me and that relaxes you a lot."
Cate Blanchett has run inside - she looks chilly in that backless dress #paprem
In a message to fans considering seeing the film when it comes out on Thursday, Freeman said: "I dare you to be disappointed. You won't be."
Richard Armitage (Thorin) on working with Peter Jackson: "He's really innovative with what he does with a camera."
Speaking about the film, Armitage said: "It's a completely new cinematic experience."