I WONDER HOW many wives have fantasised about calling divorce lawyers this week. Not with any serious intentions. But — rather in the way people who have no desire to move still get estate agents to value their homes or drag old sideboards down to The Antiques Roadshow — for the thrill of knowing what they’re worth.

The pair of law lords judgments concern two such different relationships, that at first I felt sorry for Julia McFarlane, 18 years married with three children, for being lumped in the public mind with Melissa Miller, who cashed in her short, childless union for five million quid. Mrs McFarlane deserves her £250,000 per annum, if only for making small talk with accountants at endless corporate dinners to parlay her husband into becoming partner. Whereas Mrs Miller walking away with £5,000 for every day of wedlock — kerching! — seems to merit her ex-husband’s magnificent appellation, “a spendthrift termagant”.

But if you believe that marriage is a serious undertaking, not a frivolous whim, you have to soften your view of Melissa Miller. After all, the old-fashioned girl refused to live with Alan Miller, a city fund manager, until he married her. She gave up her £85,000 PR job since he patronisingly viewed it as “play money”. The 33 months of their marriage happened to be the period in which he made £17 million. So she didn’t receive half his earnings, let alone his capital: The Sunday Times Rich List values him at £65 million. Why should he acquire her, then when bored and after he’s found a new playmate, chuck her away without compensation? Marriage is not a nebulous romantic promise, it is a contract: if Mr Miller’s morals don’t tell him that, maybe his money will.

But the Miller case is only worrisome for sugar daddies. And a prenuptual agreement would have tamed the termagant, though Mr Miller has since remarried again without a prenup: “I’m an old-fashioned romantic,” he told The Jewish Chronicle. Yes, the kind of fluffy-bunnikins who employs a barrister to calculate that running his wife over in a car would be a cheaper compensation deal.

It is the McFarlane case that gets to the heart of how we live now and thus has the most sweeping implications for not only the richest couples. Julia McFarlane, 46, met her husband at college, they were equals, on the same stellar career trajectory. Indeed as a City solicitor she initally out-earned him. But after their second child was born, they agreed she should become a full-time mother until their youngest (now 9) is at secondary school. And since 1991 she has tended to her family and her husband’s career, which flourished into a £750,000 a year partnership.

Mrs McFarlane did not foresee that her husband would fall in love and leave her for another partner at his firm. It is the stay-at-home mother’s deepest dread. In swapping your power suit for a pinny will you slay the woman he first fancied, replace her with a taken-for-granted drudge so he seeks out a new version of your sassy former self? She entrusted him with her financial future in exchange for her domestic support. He broke that deal. Why should she not be compensated with the salary she’d be earning now if she hadn’t pressed the pause button on her career?

These days a “career break” is becoming the norm, indeed — as David Cameron’s speech on flexible working proved — it is almost Conservative Party policy. Even women who once lived for their jobs are being guilt-tripped into believing it is selfish, even detrimental to their babies’ development, to work when there is no financial imperative. Moreover motherhood tends to coincide with a female mid-30s burnout caused by one too many knocks against the glass ceiling, exhaustion with the macho corporate world and a weird seemingly biological urge in the most unlikely women — myself included — to centre life more on the home than the office.

And husbands are secretly delighted, proud to be breadwinners. They swap the screeching, pop-eyed with stress, working mother for a calmer, kinder wife, maybe one who cooks the odd edible meal. And their children are happier. So long as the marriage thrives, domestic peace reigns and clean pants appear magically in the drawer, men don’t carp too much that, once tiring toddlers turn into schoolchildren, their wives’ lives get rather more cushy. Summer picnics in the park after school, hanging out with your mummy mates, doing a little painting class, spending a whole morning picking wallpaper. Hmm, tough old day then?

But if a man signs that deal he cannot, if the marriage fails, complain that he’s toiling away 12 hours a day at the company coalface so his wife can potter around Cath Kidston. She entrusted him with her security in old age, she played her agreed part at home, one that after the McFarlane judgment, is now deemed equal to his at work. Besides after many years absence a woman cannot, in many cases, dash back to her old job: her contacts have moved on, her skills are outdated, her confidence has withered. It is only fair that she is maintained until she can support herself. Julia McFarlane’s £250,000 a year is not for ever: implicit in the judgment is an assumption she will aim towards returning to work.

So what effect will this case have on how we conduct our marriages? Will it make men reluctant to let wives give up careers to look after children in case they get shafted later for loss of earnings? Maybe. Working wives are less costly to divorce. But then I see many bored, aimless yet highly skilled women who yearn to earn again now that their children are older and would be happier partners if they had a loving nudge back into work.

In The Times letters page yesterday a Lincolnshire vicar said he would refuse to conduct a wedding with any couple he knew to have a prenup because it showed a lack of trust and revealed that they regarded marriage as a contract, not a holy vow. But marriage has always been a deal, or rather a series of unique and subtle deals throughout two joint lives. The McFarlane ruling teaches us that we should think harder and talk more about our choices, not slip into them unthinkingly. It is not cold and cynical, but honest and responsible to foresee possible endings from the very start.

janice.turner@thetimes.co.uk

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