Give us a peek, luv: the world of Sarah Brown

Those miserable "adult mags" that only the British did (before the web did for them) often had a dispiriting section called Readers' Wives. Men would send in pictures (Polaroids, for fear of the man at Boots). You'd get hardened, in the wrong sense: after a bit you'd only notice the drecky sofa or the awful wallpaper, not the spatchcocked wife in the foreground.

The underlying fantasy was known in the trade as 'whoring the wife'. You'd read versions on lavatory walls in shaky felt-tip. "I am unable to satisfy my gorgeous young wife so last week my uncle/brother/mate/neighbour..."

'Whoring the wife' is something most ambitious politicians do almost by instinct; it's to his credit that Gordon Brown never did. The marriage seemed sincere. Whatever Gordon's cock-ups, we never turned on them as a couple, unlike Blair and the unspeakable Cherie.

Sarah was the human thing about Gordon, most appallingly when, almost 10 years ago, the poor people lost their baby, something so awful it's impossible to imagine, but which they handled with grace.

What we want now, though, in her diaries, is Readers' Wives. Or, rather, Leaders' Wives. We want to see the things otherwise concealed, the devices and desires behind the lace curtains of Number 10. We hope that by revealing herself, she will reveal him.

Vain hopes. We get the sofa. We get the wallpaper. But she remains fully-clad in an artful pose of normality. Just when we think we're going to get a flash, a glimpse, a naughty peek, it's obscured by a bit of domestic stage-business, a carefully-crossed ankle, an occasional table, an aide.

What we do get is the sort of slightly brittle conversation which you'd imagine would go with the crunch of Twiglets ("nibble, anyone?") in the early stages of a wife-swapping party. She tells of little domestic details (she cavils at cooking Gordon's breakfast but he brings her breakfast in bed on her 46th birthday; on October 8, 2011 Gordon comes up to the flat to get "a bit more sleep in preparation for the financial rescue plan").

She laughs at her gaffes: she shows Prince Andrew the death-mask of Cromwell (but why is showing a dead anti-Royalist to a live Royal a gaffe?) and accidentally shows Mrs Rudy Giuliani into a crockery cupboard. Piers Morgan backs into her car but says sorry. She does "wonder about the Ministry of Defence" when Gen Dannatt's wife doesn't get a thank-you note (though there are surely many, many more things to worry us about the MoD).

George Clooney is "very charming, and a properly professional famous person... it is not a bad thing, it is just noticeable among very famous people, and Mr Clooney seems to be among the best at this." She has "a cup of tea with Chancellor Alistair Darling's wife Maggie, and we agree that both Gordon and Alistair are very calm and level-headed under the pressure".

Most revealingly (but only a glimpse of stocking, dears) she writes, exhausted, "I just creep along, leaning against walls when I can" and seems to spend a lot of time bravely alone, waiting in car parks; she talks on the phone and "the evening passes quite quickly".

Readers of the Daily Mail, where the book's been serialised, have fallen for this. "Fallen for"?  Yes. I'd put money on it, if her husband's economic policies had left me with any.

In her promotional video on Amazon, Sarah Brown says she's "delighted that my book, Behind the Black Door, is coming out on the third of March. It's given me the opportunity to answer so many of the questions that I've been asked. To explain just what it's like to live as an ordinary family at one of the most famous addresses in the world."

That "just" is surely disingenuous; the "ordinary", even more so. "She seems like a very down-to-earth person," says one reader. "Seems": quite. This is Sarah, née Macaulay, co-founder of PR consultancy Hobsbawm Macaulay, a firm at the intellectual Rottweiler end of the business.

"Ordinary" just doesn't cut it, and however much her title may remind us of the 1972 porno classic Behind the Green Door, Sarah Brown is no Marilyn Chambers, and Behind the Black Door the knickers, the Jaeger suit and "my usual patent heels" stay firmly on.

What makes them do it? What makes them marry these men and then write about it? Nobody writes a book to "answer the questions" they've been asked, and though they might to answer the questions they've been asking themselves, there's little or none of that here.

So is it power? Justification? Money? A yearning for celebrity to continue? A sort of revenge Mrs Brown is too polite or circumspect to exact? Or is it just an extension of wifely duty, trying to cast a forgiving light of domesticity on a man widely, if possibly unjustly, regarded as having fucked the economy beyond all recognition?

We'll see. We need more evidence. Mrs Sarkozy. Or the ultimate Leader's Wife: Mrs Gaddafi. Now we're talking.

•Behind the Black Door by Sarah Brown. Published by Ebury Press, March 3, 2011. ISBN 9780091940577. ·