With typical gallumphing Cherie timing, we meet just as news breaks that the Blairs are buying Sir John Gielgud’s former country pile in Buckinghamshire for £4 million. So you’ve written a whole book telling everyone that you’re broke and now you own this mansion, I say. “But we were short of money at the time,” Cherie protests, “and now Tony has been lucky enough to get a job which means we can afford a country house.” Mr Blair has signed a reputed £2.5 million deal advising the American bank JPMorgan. This, plus an estimated advance on his memoirs of £4.6 million and hers of £1.5 million means that the perilous years of supporting what Cherie calls “a mortgage the size of Mount Snowdon” on their £3.5 million house in Connaught Square are clearly over.

“Yes, that was very scary,” says Cherie of this period. “Particularly since I was the person who had to support it. Because whatever else happened, we had to meet the monthly payment and it was down to me. Because no one else was going to meet it, were they?” The last sentence is said with a grim smile, since she partly did so with a series of lucrative speaking engagements in America that drew criticism that she was exploiting her status as the serving Prime Minister’s wife.

Anxiety about money is the unifying theme of Cherie Blair’s autobiography. It is why she barely saw her actor parents until she was 2 as they left her to be raised by her paternal grandmother while they struggled in touring rep. After Cherie’s flakey father Tony Booth abandoned them for good, her elegant, RADA-trained mother Gale was forced to toil in a chippie. Fiscal dread even accompanies young Cherie’s educational triumphs. How will they pay for the uniform to her smart grammar school? How can student Cherie, surviving on Dairylea triangles, afford to join the Inns of Court, her Bar exams, the compulsory dinners, even her wig and gown? The answer, always, was by winning a scholarship, by being the best.

Fast forward to Cherie and Tony, newly arrived in No 10, wondering what to do about their heavily mortgaged family home in Richmond Terrace, North London. Rent it out? Alastair Campbell, Mr Blair’s press secretary, reminds them of Norman Lamont’s tenant, Miss Whiplash. Lord Levy, a Blair adviser, says sell. So they step off the London property market just as it shoots into space. Consequently, as Mr Blair plans his departure, Cherie panics about her family being homeless. “Tony’s attitude to money,” she writes, “has always been: ‘I just want to do what’s right, and somehow or other we’ll sort it out’. ” Or rather, as the main breadwinner, Cherie would.

The truth about Tony and Gordon

Cherie Blair reveals her husband is advising Gordon Brown but says he did not trust him enough to stand down early

• 'The problem with me and Gordon is nothing personal'

• Cherie Blair: motherhood, makeovers and making ends meet – my life in Downing Street

• Cherie Blair: the secrecy and sadness behind a remarkable memoir

Multimedia

• Full coverage: Cherie Blair autobiography

Background

• My complex life in Downing Street

• Secrecy and sadness behind memoir

• Leo: my miracle baby at 45 (and yes, he did have the MMR jab)

• The night I hated Tony

Background

• Miscarriage: ‘I'm afraid the baby's dead, Mrs Blair'

• The Queen and I: relations with the royals

• Cherie Blair's face-off with Campbell over Caplin

• Peter Foster and the ‘scandal' that never was

The book is in effect a rebuttal of allegations that have made Cherie among the most reviled women of our age: that she is a greedy, grabby freebie-lover with aspirations to grandness. Her case is logical and convincing, as you might expect from a top-flight QC. But funny too: she recounts struggling in an Italian jewellery shop to prevent a bandana-clad Silvio Berlusconi, the Italian Prime Minister, from buying her an expensive necklace that would break government gift rules. And whether you believe it or not, hers is a case seldom put, certainly not by officials at No 10, who, far from defending her from criticism, routinely left her out to dry.

But now, I say, it looks as though having bought your No 10, you’re buying your Chequers. “I don’t know why they say our Connaught Square house is a mini No 10, because it isn’t really, except I don’t have my key to the front door.” Cherie means that she still doesn’t need to carry a key, since while at Downing Street staff let her in, now she is admitted by the armed policemen who guard her new home. Mr Blair will retain 24-hour police protection as long as he is considered a terrorist target, which, given his mission to the Middle East, will not end any time soon. But Cherie had looked forward to carrying her own key again: it seems to represent to her privacy, autonomy, normality.

“The house is not like Chequers except that it is a country house,” she continues. “And one thing Chequers taught us is we like getting out of London at weekends. And for the last year, it’s been a shame we haven’t had a place to escape to.” But this is a very grand house, I say, thinking of the Grade I listing, seven bedrooms, two paddocks, the 52ft drawing room. “It’s not as grand as the house next door, [Wooton House, a stately home] of which it’s the coach house, but it is a nice house. It is going to be a fantastic place to go with the children.”

I ask if when viewing this magnificent potential home she had marvelled at how far she had come from the rough side of Crosby, where she shared her grandmother’s bed, while her sister slept with her mum and Uncle Bob had a camp bed on the landing. “I think that this girl from 15 Ferndale Road has been to Balmoral, to see the Queen, to Buckingham Palace, met the Pope, had Stevie Wonder at the White House sing My Cherie Amour, how lucky is that?” It is quintessential Cherie Blair: self-mythologising and sentimental Scouser, but nonetheless a raw sense of being a working-class outsider, competing against a smooth and privileged elite, has never truly left her. “It is extraordinary that people think because I am a QC I must have lived the life that my children lead,” she says.

It has become almost a cliché to say that Cherie looks better in the flesh. Indeed, that this was said by almost everyone she met as prime minister’s wife, helped to buffer her self-esteem against the ghastly, gurning shots chosen by newspapers. Today at Matrix chambers, she looks handsome in a white print shirt-dress bought in Selfridges (which her daughter Kathryn is delighted to discover is walking distance from Connaught Square). Her often cussed hair was primped this morning by her faithful André, a minor hero in the book, into perky flicks. She looks fresh and well slept, younger than 53, trim waisted with the broad bottom she rails against in her book. On television her frantic animation, the way she clasps your hand with both of hers, the intense, round-eyed gaze, can appear somewhat deranged. But TV tunes out her girlishness and northern warmth.

Cherie-haters often focus upon her mouth. That it is large and constantly moving, with a dissatisfied downward turn in repose seems the outward expression of her perceived flaws: greed, complaining, tactlessness, that she never bloody shuts up. But that same mouth emits a low, mellifluous voice, with a bit of Liverpool in her occasional “everythink”. And it is mostly upturned in a pleasingly gamine smile or emitting a honking, ready laugh, which she partly employs as a stalling tactic when tackling tricky questions.

Listening back to my tape, I realise that I am unusually forceful with her, even rude. I cannot help venting my personal sense of betrayal, and that of many working mother friends. I tell Cherie how delighted we were when she arrived at No 10, that she had kept her name and career, had a marriage of equals, muddled through family life. She was like us with her Ken Dodd morning hair, picking those flowers from her doorstep. But then the “Oh Cherie!” moments began, multiplying towards the end, when we longed to shake her back to sense. To Cherie’s credit, she takes all this rather equably.

Let’s take Carole Caplin, I rant. When you had the choice of every discreet fashion adviser in Britain, why did you trust someone so obviously dodgy? “Carole isn’t dodgy at all,” says Cherie mildly. “In fact, the one thing you can say about Carole is, although Alastair was convinced she was going to do kiss and tell, she has never kissed and told.” But wasn’t she restrained by a gagging clause? “Well,” she splutters, “I hadn’t even thought . . . Yes, it is true Carole had a confidentiality agreement, but so did my nanny and I had to take her to court to enforce it.” (The Blairs’ nanny Ros Mark was injuncted to stop a proposed book about their intimate family life.)

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