“I had this sense of total physical inadequacy,” Ian McEwan says about how he felt after appearing at this year’s Edinburgh International Book Festival, in August. When he left the event, “There were four or five incredibly athletic guys doing splits on the carpet.

“I had to step over these muscled legs and gleaming bodies. They were trapeze artists. They were about to hurl themselves through space. And I thought, Wow, I would rather have watched these guys!”

Others disagree. McEwan, who is now 77, is one of the UK’s leading novelists, and he attracts big crowds. About 1,000 people came to his Edinburgh event; when I met him at Ennis Book Club Festival, in Co Clare, in March, he had an audience of 500.

Appropriately, the value we place on writing is one of the themes in his new novel, What We Can Know. The book comes in two parts. In the first, set in 2122, an academic, Tom Metcalfe, is investigating a great lost poem by the fictional poet Francis Blundy.

Blundy read the poem, A Corona for Vivien – a verse in 15 sonnets – to his wife at a dinner party in 2014, then presented her with the only copy. The poem was never heard nor read again. But Tom thinks he can find it.

The second part of the book it would be wrong to reveal, but it highlights, as the title suggests, the gulf between what we think we know and what really happened.

The setting of early-22nd-century Britain gives McEwan the opportunity to make some pr