Philip Pullman directs me towards a chest of drawers in the corner of his sitting room. “Top drawer. That box. Go ahead, open it.”

Inside lies an award: it’s nothing to do with the Oscar that The Golden Compass, the film of his best-loved book, won last month, nor the Whit-bread award that he accepted in 2002. This is a Distinguished Flying Cross – given posthumously to his father, an RAF officer who died when his aeroplane crashed in Kenya in 1953. A photograph of the handsome young pilot, his face dominated by a magnificent moustache, stands on a nearby shelf.

“I don’t really know what happened,” says Pullman, slowly. “I was seven at the time and, of course, I imagined him a hero. But it seems it may not have been an accident. There’s even some suggestion it was deliberate. Certainly, he had been drinking. I only learnt about what happened long after I’d grown up.”

Momentarily confused, I ask a question that I instantly regret: “They give you a medal for crashing your plane?”

He gives a snort: “No. For deeds of valour, honour and courage.”

The story has a certain resonance, given the subject of Pullman’s long-awaited new book, Once Upon a Time in the North – an old-fashioned yarn of derring-do that opens with a crash-landing in a dismal Arctic trading post. The pilot – who happens to be a dashing young man with a magnificent moustache – is cowboy Lee Scoresby, one of the best-loved minor characters in Pullman’s His Dark Materials trilogy. By the end of the book he has fallen in love, befriended a talking bear, triumphed in a nail-biting shoot-out and generally made the world a better place.

At first glance this is a traditional Boy’s Own tale: indeed, Pullman freely admits that he lifted the plot from his favourite western, The Magnificent Seven: “A great film. I’ve plundered it before and I expect I shall plunder it again.”

Pullman’s books – which have sold 5m copies in this country alone – are seldom as simple as they first appear. “It wasn’t until I was some way into it that I realised: it’s about honour . . . Of course,” he concedes, “the story is old-fashioned, but then stories are old-fashioned things. People have been telling stories about combat, about honourable behaviour, about the temptation to be dishonourable for 3,000 years, so I’m not doing anything new.”

He is too modest. Although the book may look at first glance like a straightforward spin-off from His Dark Materials, the differences are as marked as the similarities.

While the evil forces of the trilogy were all linked to an oppressive theocracy, their equivalents in Once Upon a Time in the North are allied to an oil corporation that is trying to buy up politicians and subvert the rule of law.

This is evidently a subject close to Pullman’s heart, for he talks with angry animation about “the despoliation of the planet caused by prospecting for oil” – and his hands clench as he does so.

I observe lightly that humans have always needed something to dread, whether it’s a barbarian invasion, the Inquisition, the red menace or the atom bomb. And since global warming is now the subject du jour, it’s inevitable that it should be the focus of our fears. He sits up straight in his leather armchair.

“No, it’s different now. Of course, a Turkish or Lusitanian peasant tending his olive trees during the heyday of the Roman empire would have been worried that the Romans would come and crucify him or the barbarians would burn down his villages. But he never feared that the entire globe was going to be destroyed, ruined, rendered uninhabitable. Now we do feel that – and we know it. And that’s more scary than things have been in the past, isn’t it?”

I can’t help feeling that for a Lusitanian peasant, a bit of sacking and looting, done thoroughly, might seem just as dreadful as global meltdown, but Pullman is on a roll: “You see, there’s nowhere else to go now. In the 16th century there was another world. In the 18th century there was another world. You could go to Australia, a huge big continent, full of possibilities. Ruined this place? Don’t worry, there’s another over the horizon. But we know that’s not true any more.”

As part of their own small contribution to the war on global warming, Pullman and his wife are having a ground-source heat pump installed in their home, a 17th-century farmhouse near Oxford: “It’s costing a fortune, but it will eventually mean that we burn much less fuel. I can only afford to do it because I’ve got enough money. There should be one in every house in the country – and there would be if the government had the sense to invest in such things. But they lack the courage to break away from this insane obsession with the market. They worship the market. It’s desperately destructive.”

His solution is both drastic and nostalgic, harking back to the era of his birth in 1946: “In the second world war people wouldn’t of their own accord have restricted their eating, so we had rationing. And it worked, because it was universal and everyone had the same rations and you couldn’t buy and sell someone else’s rations.” So we should bring back rationing and to hell with the market? “Absolutely.”

Tellingly, the good guys in Once Upon a Time in the North are customs officers. Pullman must be the only member of the super-rich who can imagine a taxman as a hero.

Yet I’m not sure how deeply he really believes in the power of the state to reform us, for he is highly critical of the government. A former teacher, he is no fan of endless state intervention in education – and the mere mention of the scheme to impose “five hours of culture” on schoolchildren makes him howl.

“It’s utterly ludicrous. When I was a boy at school in Wales, the teachers were cultured people. The head-master was an astronomer, the deputy head was a poet who had won prizes at the eisteddfod. They were people of consequence. But these days teachers can’t be of consequence because they haven’t time. They haven’t time to bloody read, let alone to write poems that win prizes.”

Pullman honed his own skill as a storyteller in the schoolroom: “I learnt everything about stories from telling them out loud to children – stories from the Iliad and the Odyssey, that sort of thing. I could make them want to know what’s happening next, I could make them see what I described, but I wasn’t so good at making them laugh.”

Children, he says, “hunger for stories and stories are what they remember”.

And the Old Testament? “Wonderful stories!” he cries. He clearly loves them just as much as his Christian critics do, but there the resemblance ends: “They don’t regard them as stories; they treat them as scientific truth or history. They have forgotten how to read.”

The allusion to his Christian critics makes Pullman, who has spent much of the past year dealing with The Golden Compass, the £90m film of the trilogy’s first book, look weary. The movie’s poor US box office, following a boycott by fundamentalists, has cost the jobs of the studio heads responsible; now, plans to film the next books are uncertain. So, funda-mentalism, one: storytelling, nil?

“The hoo-ha in America was entertaining really, very baffling. People got the wrong end of the stick so conclusively – all you can do is enjoy the spectacle,” he says.

New Line Cinema, which made the film, did not attempt to rein him in while he was promoting it. Frankly, there would have been no point: the internet was already ablaze with inflammatory Pullman lines, culled from old interviews, including “I’m trying to undermine the basis of Christian belief”. And although he did moderate his tone late last year, telling America’s Today show that his atheism was not of the preachy kind, there was nothing he could do to damp down the row.

Now, of course, he has different preoccupations. “Humanity needs to evolve morally if it is to survive,” he insists. “We have to change and it will be very uncomfortable. But if we don’t, the alternative will be worse.”

And just who is going to get humanity to evolve morally? It’s unlikely to be either the church or the government. But I have a strong suspicion that it’s a job that Philip Pullman, storyteller supreme, is determined to make his own.

Philip Pullman will be speaking at The Sunday Times Oxford Literary Festival on Monday, March 31 at 7pm. To book, go to www.ticketsoxford.com or call 0870 343 1001

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