If the festive season has left you unable to look a tin of Quality Street square in the chops ever again, spare a thought for the cast of Allelujah!, the Alan Bennett play staged this year at the Bridge theatre in London, its first preview taking place, in suitably bathetic fashion, on the night that Croatia sent Gareth Southgate’s warriors crashing out of the World Cup. After the final performance, Bennett reveals in the annual excerpts from his diaries published in the London Review of Books, he arrived backstage to find the actors overwhelmed by the nation’s favourite chocolates, “sent by Nestlé because they’re mentioned in the script, though only as part of the contents of a deceased patient’s locker. Next time I must try and think of something more exotic.”

Bennett’s diaries are popular – to the point of addiction – precisely because they combine the mundane and the exotic: a love of aconites and mild exasperation with the way cafes make egg-and-cress sandwiches these days (too much bread, not enough filling) mingle with accounts of a visit to a Gothic abbey in France, anecdotes of Dudley Moore’s antics in Beyond the Fringe and memories of being photographed by Richard Avedon. And underlying much of his writing, both here and elsewhere, is an acute sense of trying to work out where and how he fits in or doesn’t – with other people, in the social order, as an artist – and a sense of rueful self-consciousness that he should be doing such a thing in the first place.

It occasionally manifests itself in the way Bennett talks about books. Musing on the comfort afforded to him by the installation of a “slightly larger radiator” in his downstairs loo, he thinks of Nancy Mitford’s The Pursuit of Love, in which junior aristocrats would gather in the airing cupboard, it providing a warm haven from the chilly corridors of their stately home. But Mitford’s thinly disguised alter egos termed their bolthole the Hons’ Cupboard; the spare lav is a somewhat déclassé version.

Bennett also finds himself glancing at Richard Hoggart’s Promises to Keep, in which the author of The Uses of Literacy finds himself assessing the insights that accompany old age. Among other things, Bennett notes, “he mentions not feeling he belongs to ‘the English Literary Happy Family’, as I hope neither do I”.

It’s not entirely clear who the members of that family are, since writers are not often remarked on as either particularly happy or particularly familial, but in Bennett’s case it might have something to do with a suspicion of in-groups. He is tickled when his publisher tells him that one of his son’s friends, who lives in Greenwich Village, has a tattoo of Bennett on his arm. It might, in another voice, seem edged with boastfulness were he not so clearly wise to the pitfalls of reputation.

Writing after the death of Philip Roth, Bennett is struck by the impulse to capture, and perhaps to constrain, the celebrated: “Supper and a very funny episode of Friday Night Dinner. Much in the papers about Philip Roth, with the commentators feeling bold enough to say what they were nervous to say while he was alive. It’s like tying down Gulliver, which now that he’s dead it’s quite safe to do. At long last he can be pocketed.” One feels that Bennett’s way of pocketing Roth was to relegate his report of his passing to after Friday Night Dinner.

During 2018, Bennett also enjoyed the Booker-winning novel Lincoln in the Bardo, by George Saunders, Roland Philipps’s book on the Cambridge spy Donald Maclean and Antony Beevor’s Arnhem. But he reserved his highest praise for the poet Andrew McMillan, whose second collection, playtime, he read in a single sitting. McMillan’s descriptions of youthful sexual identity struck a chord with Bennett; some poems, he wrote, “I wish I had written or had the courage to write, particularly the failed encounters – with a man sheltering from the rain in a telephone box or a youth on the train dozing in the seat opposite. Were this Alexandria not Barnsley they might be by Cavafy.”

Of course, one might not have so much cause to shelter from the rain in Alexandria but that, again, is the point; the exotic – the fleeting glimpse into another’s life, the moment of desire – can happen just as easily in Barnsley, especially if followed up by a properly assembled egg-and-cress sandwich.

• Alex Clark writes for the Observer