My blue movie scare when I was married to a Home Secretary

I've written three novels about a fictional female politician. In my first she was a newly appointed minister who got her private life in a terrible tangle after her husband gave her a particularly tricky time through his dealings with a property speculator.

It led to her having to defend herself on the floor of the House. That book was published just before Tessa Jowell separated from her husband, whose work-life had caused similarly acute political problems.

My fictional minister has become Home Secretary in my latest book. She was appointed to that high office (in the writing of the story) about a week before Jacqui Smith was in real life. I felt a bit peeved at the time. I'd wanted my character to be the first female Home Secretary, not pipped at the post before appearing in print. In the new book she has remarried, to the editor of a national newspaper and thus a potential security risk.

What I do know is that trust and betrayal are fatally combustible in work as well as in the bedroom. When the two collide it is almost always with devastating consequences.

The tension of high ambition being unfairly floored by low behaviour is what defines this real-life scandal and, as a wife of a former Home Secretary, I can only imagine the total discomfort of their situation.

More difficult grey areas come when jobs are interlinked - husbands working for wives. Things getting overlooked in a busy minister's life, papers signed in a rush, male frustrations Just what does a powerful woman MP do when humiliated by her husband in the way that the Home Secretary has been?

Seeing his private indulgence portrayed in such a devastatingly public way obviously undermines the very essence of a bond of trust. It would be enough that she overlook his porn habit but to skewer her career by allowing it to become publicly funded is harder to forgive. In political marriages you expect, in this digital age, unwelcome intrusion but what your husband does when you are not there you never hope to see become political fodder.

I once found myself in a potentially compromising-for-political-spouse situation. I was being put up in a Manchester hotel, speaking at a dinner. Turning on the television while changing it came as a considerable surprise to catch the end of a (very) blue movie. It must have been the tail end of the film a previous occupant had been watching. The jackpot question, thinking about it in retrospect, is whether it had shown up on the bill that was settled by my hosts. I'll never know. It could certainly have given rise to a lot of explaining - especially had my husband still been Home Secretary.

It may be true that all politicians spend their lives walking on eggshells - but I can't help thinking that for women the eggshells are even easier to break. You not only have to stay out of trouble yourself, you have your partner to think about too.

I can understand why some women are driven by ambition and are willing to put up with it all. I admire them, I just thank my lucky stars I'm not one of them.

I'm often asked if I've ever thought of becoming an MP. The mind boggles: I can hardly make a decision about whether to walk or pump up my bike tyres, let alone come out with sane views on quantitative easing. However, more articulate women than me can hold great offices of state - but they must be a tough breed because, huff and puff about it as you might, the playing field isn't level: a male MP can brush off embarrassments like his wife's "calendar" past a lot more easily than the other way round.

I can remember sitting next to Peter Bottomley in the Lords Gallery one State Opening of Parliament when we were both married to ministers. He turned to me with a wry smile, palming his named seating card. It read: "Mr Virginia Bottomley". As a senior MP in his own right, I could understand him feeling wry, but my card read: "Mrs Michael Howard". There was a certain symmetry It's an archaic naming practice either way, nowadays, but it is symbolic of the peculiar difficulties of being the spouse or partner of a high-profile woman.

Sandra Howard's latest novel, A Matter of Loyalty, published by Simon & Schuster, is out now. £12.99.