Bringing together two of my favourite subjects – French literature and nuns – this was always going to feature in my top 100. It’s not my number one nun book – that would be The Nun of Monza by Mario Mazzucchelli, which is non-fiction – but it is a fascinating, hilarious and moving literary oddity. Diderot wrote it, apparently, as a joke – a series of letters from a young girl unhappily incarcerated in a convent, begging for help – and it was only published posthumously. In part, it’s little more than a heavy-handed attack on the church, with a certain amount of gleeful sado-masochism chucked in for good measure. But I always had the impression that Diderot got much more involved with la pauvre Suzanne than he intended to, and once you’ve got past the scandalous stuff it’s a very moving and persuasive account of youth destroyed by age, innocence corrupted and Christian morality undermined by sexual perversion. I don’t think I’ve ever seen La Religieuse in any lists of early LGBT fiction, which is a bit weird, because the main emotional and sexual relationships in the book are entirely between women – and Diderot doesn’t hold back.