When producer Rod Brown (Dream Team) and director Vadim Jean (Leon the Pig Farmer) visited Sky to discuss their dream of bringing Hogfather, the 20th novel in Terry Pratchett's much-loved Discworld series of novels, to the small screen, they knew they were facing some significant hurdles. Even when Sky was responsive to the ambitious idea, Brown and Jean knew that there was one person who could make or break the project from moment one: Terry Pratchett himself. Over the years Pratchett had resisted approaches from American production companies to bring the Discworld to life.

'I had a three-hour meeting with Terry,' explains Rod, 'and I went through with him what we wanted to do with the story, and I think the fact that we had really done our research, in terms of what we would leave in and what we would leave out, made him realise that we were serious.' Pratchett gave the go-ahead.

Once Pratchett had given his blessings to the project, Sky approached Hallmark International to share production costs and secure international distribution. Hallmark has an unrivalled reputation when it comes to fantasy family drama, always boasting high production values. Once the budget had been established, Vadim started to work on a script adaptation, and Rod and Line Producer Ian Sharples went ahead to assemble the cast and scout for locations.

'We found out that David Jason was a huge Pratchett fan,' laughs Rod. 'We sent him the script and he got back to us and said he was in. He hasn't done a major comedy role for a number of years. This is him, after A Touch of Frost, getting back to his comedy roots. Watching him on-set on a day-to-day basis is funny. He's so entertaining and very professional. He's a joy. Joss Ackland wasn't a Pratchett fan, but his grandchildren were. When they heard he was up for the part as Ridcully, they rang him up and told him that he had to do it.'

The production team went to work transforming stages at Three Mills Studio in East London into elaborate key interior sets like the Tooth Fairy's Castle, where over 160 cubic metres of polystyrene, a million teeth, 400,000 watts of light and 85 miles of scaffolding were employed to dazzling effect.

Throughout the whole production process, the team were keen to involve Pratchett at every level.

'Many times during pre-production or the shoot, if we had any questions we contacted him,' says Ian. 'It's just the way we've worked. We're custodians of Discworld, and it's important that we stay true to what he wrote.'

In addition to being the first Discworld book to get a proper high-profile adaptation, Hogfather marked another significant step for UK television drama: It was the first production shot with High Definition cameras, signalling Sky's commitment to unique and innovative HD programming.

'One of the things that comes out very strongly if you read Pratchett is all the little details he mentions,' says Ian. 'Little things like the doorknobs in the Tooth Fairy's Castle are designed with intricate gears and levers. Those are all little things that come across in the book and we were very keen to do this.' Rod agrees. 'It's very rich - the fact that it's shot in High Definition will give it a really detailed look.'

And Vadim was also keen to cut big CGI effects to a minimum, preferring instead to pump as much quality onscreen as possible: 'We've done a lot of effects by slight of hand, which Hollywood would never have done.'

At the end of the production Vadim is relieved: 'The schedule has been really tough. In effect, we've trying to make Lord of the Rings without a Hollywood studio, so it's been tough. I've been working most days from 6am until midnight, so physically it's been draining.'

But Rod has no doubt that all the hard work will pay off. 'We're visuals-led, and also performance-led. The people we've put together bring these characters to life, and they're all at the top of their game. I think that you can't compare it to anything else on TV, and you'll find it visually more interesting - and performance-wise it's really stellar.'