"One of the best known atheists?" Pullman is looking bemused, "well I certainly don’t think of myself like that. I’m a storyteller. The atheism is something incidental. It would be a great pity if I was known mostly for my atheism and the storytelling was incidental."

It definitely isn’t his religious point of view which has had him acclaimed as one of Britain’s greatest writers ever since the publication of Northern Lights in 1995, the first part of the His Dark Materials trilogy. Nor is it the reason why the opening words ‘Lyra and her daemon’ evoke an entire world for anyone who has read it. And yet it is equally impossible to deny that there is something fascinating about having the imaginative audacity to kill God in one book and to turn Christ into a brother who betrays Jesus in another.

The most common misconception about Pullman is that he is anti-religion. He’s isn’t, he just happens not to believe in God. What he has a problem with is any person or organisation who dangerously abuses their power. In his new book, The Good Man Jesus and the Scoundrel Christ, Jesus is violently opposed to the idea of a church being created in his name, despite the arguments that his brother Christ puts to him. "[Christ] says several true things. He says the church will do great good, it will help people, it will educate, it will look after the sick and dying. But at the same time there is a price to pay and the price is this: individuals will be tempted by the power that they have and the organisation itself will be tempted to decide what is true and what is false and who is a heretic and who is not. And once you have the idea of heretics you have the idea of punishment."

He argues that the whole concept of heresy can only exist in a "totalitarian state", though not necessarily one which revolves around God. "The perfect example of a theocracy was Soviet Russia, which was explicitly atheist. They had a holy book, which was the works of Marx. There was a priesthood, the Communist Party, which had privileges denied to the laity and secrets which they kept to themselves. Those who worked against them were heretics and there was a whole state sponsored organisation of denunciation and betrayal, trial, confession and execution - exactly as you had with Renaissance Italy and Spain."

While he is extremely appreciative of living in a society where he write can and say what he likes, he despises the current Labour government’s "Stalinist instinct to see what everyone’s doing and tell them to stop it". The Tories have said that they would roll back many of Labour’s more invasive data-collecting initiatives, but Pullman is sceptical.

"Give them a few years in power and let them see what the technology can do. The trouble is that it’s so tempting and you tell yourself that you’re only it doing so that you can look after people and make sure they’re safe – and that they’re not going to get up to any trouble in the future." He looks around outdoor café we’re sitting in. "I have no doubt that we’re overlooked at this moment by a CCTV camera. This is a sad state to have got ourselves in where you can’t go about without knowing that somebody’s looking at you."

Pullman has a habit of staring gravely at you while you talk, giving serious consideration to each question before responding in a voice which combines gravitas with clarity, so that there is a quiet intensity and conviction to everything that he says. You don’t want to stop listening, but it is a little intimidating.

On top of this there is the confusion of his voice being so familiar to anyone who ever listened to the award-winning audiobooks of His Dark Materials, which Pullman narrated. "I really, really enjoyed making that audiobook. It was hard work, but the craft of it is just wonderful to watch and the director assembled such a great cast of radio actors, and attended so closely to every little detail. If there’s a comma in a sentence, he wants to hear the comma, because it’s there for a purpose."

When he talks about Jesus you can hear a similar admiration of craftsmanship, the respect that one storyteller has for another. "He was a man of profound imagination and the power of synthesising complicated moral points into simple brilliant images, which work however they are translated. He was unequalled in history I think. And the great pity of it is that he was crucified before he had the chance to write a book."

While Richard Dawkins argues that inculcating a child with a religious belief is tantamount to "child abuse", Pullman speaks warmly about the fact that "every turn in my mind, every way I form thoughts was formed by listening to the stories from the Bible, the liturgy of the prayer books and singing the hymns in church every day when I was younger." He believes that "if it is of comfort to a child then there is no reason for them not to believe what they want to believe" putting his trust in the "natural progression of scepticism and intellectual curiosity" which is likely to occur as they grow older.

"I think that Dawkins – for all his merits – does have a very slight tendency to be literal minded about fairy tales. He said once that he wonders what is the effect of parents teaching children that princes can become frogs and so on. But there’s no actual teaching going on. It’s the immense power of let’s pretend, once upon a time - which is such a wonderful thing in anybody’s life, especially in a child’s. And its effect on a child’s life who doesn’t have it is no where better described than in Bleak House, where Dickens talks about the money lender’s children who are brought up without any fairy tales and without any nursery rhymes - without any stories whatsoever. And the effect is that they don’t seem like children at all but like elderly monkeys with something depressing on their minds."

He is as passionate discussing the ability to tell stories with pictures and on screen as he is discussing literature, and becomes particularly excited when I ask if he is interested in graphic novels. "Very! Hugely! Passionately!" he replies, "I love the medium. It’s magnificent and underappreciated." He wrote a comic two years ago about the sea bound adventures of a boy called John Blake and has now turned into a film script. "I’ve just signed a big contract for it. And all we need, really, is two hundred million dollars and a fourteen year old Burt Lancaster – who will guarantee not to look any more than fourteen for the next ten years so we can do sequels." Unlike The Golden Compass, this time he’ll be in control as one of the producers. And unless John Blake has a battle with Jonah’s whale, the storytelling, rather than the religious implications, will be all that anyone is discussing.