Nothing is sacred when Cherie has bills to pay

I've heard of people saying they almost died of embarrassment, but getting pregnant? According to Cherie Blair, her youngest son, Leo, was conceived at Balmoral because she was too embarrassed to take her "contraceptive equipment" on a prime ministerial weekend. I'm not sure what this "equipment" was - I always managed with a foil strip of pills or a packet of condoms, either of which slipped handily in a pocket - but Mrs Blair was eager to conceal it from the royal servants who'd unpacked her bag on a previous visit.

Quite what her Leo will make of this when he is old enough to read Mrs Blair's book is anyone's guess. Teenage girls often give a variety of excuses for accidentally getting pregnant, but this must be the first time in history it's happened because a woman didn't want the servants to know she was having sex. Mrs Blair was the prime minister's wife at the time, not a tongue-tied teenager, and the revelation is not going to endear her to women who feel some responsibility to act like grown-ups.

The larger question is why a woman who fiercely guarded her privacy when she lived in Downing Street has suddenly decided to expose the most intimate details of her life to public gaze. The short answer is that she has a book to sell, and she has to provide something in return for an advance reputed to be £1.5 million. Since Saturday, when serialisation of her autobiography began in two national newspapers, we've heard about her financial anxieties - including a "mortgage the size of Mount Snowdon" - and her feelings about her miscarriage after the birth of Leo.

It's a hugely unedifying spectacle. And if Mrs Blair imagines that it will cause the public to warm to her, after years in which she was criticised for accepting freebies, she could hardly be more wrong. Her willingness to transcend just about every boundary of taste, to settle old scores and expose intimate details of her private life suggests that she is still at heart an anxious working-class girl who doesn't know where the next penny is coming from.

I have some sympathy with this, coming from a similar background myself, but most of us get over it. Mrs Blair's harping on her financial problems, and her readiness to spice up her autobiography in this way, reveal a psychological state that doesn't have a lot to do with reality. Worse, her candid remarks about Gordon Brown are doing incalculable damage to the Labour Party. As it happens, I'm convinced that the Prime Minister has to go, but in an orderly manner which won't be helped by this torrent of revelations. Mrs Blair may be thinking primarily about her bank balance, but at huge cost to her reputation and the party she professes to love.