Pullman has been simultaneously accused of making his fictional worlds too morally simplistic, and of being morally confused, allowing good characters to do dubious things. Lord Asriel, for example, the main protagonist of Northern Lights (1995) (published as The Golden Compass in North America), sacrifices a child. But, compared with his Oxford forerunners — Tolkien, Lewis and the other ‘Inklings’ who met at a pub down the road half a century ago — Pullman is happy not to be on the side of the angels. ‘Nothing in The Lord of the Rings is overtly Christian,’ he says, having explained to me how Tolkien was a ‘cradle Catholic’ who believed in the authority of the church. ‘But you can see a sort of absolutism in the way the bad characters are very, very bad, and the good characters very, very good, and the only interesting character is Gollum, who is good and then bad.’ He contrasts this with Lewis: ‘For the children in the Narnia books, the temptations they face — should we eat these marshmallows or not? — are real temptations. This is why I feel more akin to Lewis than Tolkien… I respect the struggle.’

Nearly all the influences Pullman has cited so far have a religious background, and so, inverting Blake’s comment on Milton, I ask him: ‘Aren’t you really of the believer’s party without knowing it?’ He’s amused by the thought. ‘I probably am,’ he says. ‘I’m religious, but I’m an atheist. I think religious questions are the big questions. Where did we come from? What is life about? What is evil? Those are questions I do think about.’

Often billed as a key figure of the ‘New Atheism’ movement, Pullman says that he met the writer and polemicist Christopher Hitchens only a couple of times, and that he admires Dawkins’s writings on science — although he completely disagrees with him on fairy tales, which Dawkins described in a TV interview in 2008 as ‘anti-scientific’.

Pullman’s own retelling of Grimm Tales for Young and Old was published in 2012, and he subscribes to Einstein’s dictum: ‘If you want your children to be intelligent, read them fairy tales. If you want them to be more intelligent, read them more fairy tales.’ ‘It’s all about thinking by analogy,’ says Pullman, ‘and analogy is an enormously powerful tool in science. Einstein, when he was thinking about light, imagined himself riding on a beam of light.’

‘I like to say I’m a complete materialist but…’ Pullman allows himself an English teacher’s dramatic pause, ‘matter is conscious. How do I know that? Because I’m matter and I’m conscious.’ Once again, Pullman opts for complexity and nuance, and you can hear the same dislike of hierarchies in his critique of some popular science. ‘What you often get in people of this stripe (and Brian Cox — the TV physicist — goes in for it as well), is a sentence of the formula “X is no more than/just/merely/nothing but Y.” For example: “The world is nothing but the action of molecules” or “Love is merely the movement of electrons in the brains.” Sentences of that sort are nearly always mistaken,’ says Pullman. ‘I would prefer they were put in the form of “Love is a movement of electrons in the brain, among other things.”’

‘Among other things’ would be a great motto for Pullman’s ambivalence (or should that be multivalence?) about matters of belief, fiction and science. He is of the old school of secularism which holds that faith should be kept out of the public sphere, but still refuses the kind of inquisition that seeks to root out mistaken beliefs: ‘What you feel and believe are private to you and belong to nobody else,’ he counters. ‘What you do in the public sphere is what’s important.’