We all know Edwina Currie as a shrill, tasteless, attention-seeking Thatcherite nuisance from Liverpool. But the private Edwina —  as revealed in her Diaries: Volume II, 1992-97 (Biteback, £20) — is thoughtful, engaging, witty, kind-hearted and, politically, very astute. Has anyone framed a neater analysis of John Major’s idiotic ‘Back to Basics’ drive than this? ‘It outlawed the one protective factor the Tory party has always relied on — hypocrisy.’

She watches senior colleagues plotting to replace him during the mid-1990s, and she sums them up with lethal concision. Michael Portillo: ‘very steely, very cool, very unpleasant’. Ken Clarke: ‘fine brain … lazy character’. John Redwood: ‘disloyalty is his only trump card.’ Michael Howard: ‘God, if the party choose him it’ll be in the wilderness forever.’

The pathos of the book lies in Currie’s conflicted attitude to John Major, her former lover, who refused to give her the promotion she craved. She describes him shuffling into the Commons tea-room to load his tray with ‘pork pie and beetroot, ugh!’ and then sitting amongst colleagues and whining about the press. ‘The PM is more stupid and ignorant than ever I realised. He’s just dim, period. It’s a disgrace.’

And yet, she’s still carrying a torch for him; she indulges in daft fantasies about serving as his secret mistress and turning his premiership into a triumph. ‘I’d have tutored him and pushed him and kept him going … and I would have loved it. And him? We’ll never know.’

Even if you have to read this in secret, don’t miss it. It’s riveting.