WITH his wide blue eyes, bushy white beard and small frame, you could say Sir David Jason was born to play a cheeky misfit wizard.

In fact, it turns out the well-loved actor has been hankering to play Terry Pratchett character Rincewind for decades, ever since he first read the comic fantasy The Colour Of Magic 25 years ago.

"I remember reading it when it first came out and I just fell in love with the whole concept," the 68-year-old says.

"The central character was this failed wizard who'd got a spell from the famous spellbook Octavo in his head. He was just such an amusing, endearing character and the driving force behind the book.

"The whole magic and invention of this world, the Discworld, just got straight to me and ever since then I just wanted to do it."

Sir David held firm to this hope and then one day, as if by magic, he got a call from production company The Mob, who were behind the Sky One adaptation.

"I always kept this idea in my head that one day I would play Rincewind. But I never really thought that television could make it. I thought it was only something that big budgets could afford.

"It wasn't until The Mob came along and made an offer that I couldn't refuse – I've always wanted to say that! – we finally got it on the screen. They've done a brilliant job."

The Colour Of Magic combines the first two books in Terry Pratchett's long-running Discworld series – including follow-up The Light Fantastic – and takes us on a fast-paced adventure with Rincewind and his unlikely companion Twoflower, played by Lord Of The Rings star Sean Astin.

Sir David says it's their unusual 'buddy' relationship that makes The Colour Of Magic so funny.

"The central thrust of most comedy in a two-character relationship is one knowing fool and one unknowing fool," says David, citing Laurel and Hardy as good examples.

"You must have a balance, an opposite, like a ying and a yang. Where Rincewind and Twoflower succeed is that Twoflower is a totally naive tourist and Rincewind is very streetwise."

The first instalment of the two-parter was shown over the Easter weekend, showing Rincewind and Twoflower stealing horses to escape a burning city, riding transparent dragons and swimming for their lives to avoid being sucked over the edge of the world. All impressive stunts for an actor nearing his 70s.

"There were certain elements that we obviously didn't do, because I can't really ride a horse that well," admits Jason. "But basically everything else, both Sean and I did at least half if not three quarters.

"The bit where they go over the edge of the world, that was us.