My Oxford tutor, J I M Stewart, aka Michael Innes, was an easy-going man as a rule, but he couldn’t be doing with C S Lewis. Stewart was a sceptical Scot of bone-dry humour and fey imagination who baulked at Lewis’s dogmatic manner. ‘I could have put up with Jack’s constant references to the Almighty,’ he would say, ‘but not with the implication that God returned the compliment.’

Having been even more bored by the Narnia novels as a child than I was by The Hobbit, and force-fed The Screwtape Letters and The Problem of Pain – a book Lewis came to regret, according to the author of this new biography – at school, I applauded the witticism even when I discovered that it wasn’t original. Only Lewis’s day job interested me. Most English academic critics at the time were textual commentators or bug-eyed Leavisites, both indifferent to the cultural and historical background of literature and actively hostile to any religious connotations. Neither approach appealed much to one such as myself who day-dreamed his way through university life. There were exceptions – John Jones, for example, who lectured on Hegel and wrote a fine book about Aristotle – but such people were considered eccentrics who belonged in other faculties: strange, out-of-the-way places like the philosophy school. And although the exchange with my tutor took place during the annus mirabilis of 1968, when a literary and political revolution was sweeping Continental Europe, England remained – as usual – largely immune to such excitements.

Lewis was different. Subscribing as he did to the traditional view that literature is meant to instruct and entertain – to instruct by entertaining – I can’t imagine him having any truck with the rise of theory had he survived to see it; but at least he took a broad,