When someone in authority says “these reforms will bring the law into line with public expectation and attitudes”, you know that it is time to worry. Those were the words of Professor Elizabeth Cooke, of the Law Commission, as she proposed a change in the law to give the surviving half of an unmarried couple the automatic right to inherit a proportion of their late partner’s wealth. At present, unmarried couples who die intestate may have to go to court when one dies and can face a challenge from their partner’s family.

At the risk of sounding like an outraged Victorian parson snooping through the windows of cottages on the lookout for couples living in sin, I can’t see a problem with the law as it stands. Yes, it does make life difficult for couples who can’t be bothered either to get married or make a will. But there is every reason why the law should encourage marriage.

It is not a case of moralising, but money. Couples who get together without making a legal commitment to each other cost taxpayers a fortune. One in two cohabiting couples with children break up before the child’s fifth birthday, compared with one in 12 married couples. The result is thousands of extra single-parent households, with associated costs in welfare benefits.

The Law Commission claims that its proposal would not undermine marriage. Nonsense. The changes would give couples a huge financial incentive not to marry. At present cohabiting couples do not enjoy the inheritance tax benefits of married couples, under which the survivor can inherit their spouse’s entire estate tax-free. But they can fiddle themselves an equally valuable tax break: by pretending to be living apart and claiming a capital gains exemption on two “main homes”, rather than one. If cohabiting couples are to be given the inheritance rights of married couples they will be able to claim both exemptions. And you can bet that they will.

For any cohabiting couples who don’t like the inheritance laws there is a simple answer — get married.

It takes five minutes. You don’t have to dress up, hire a carriage or invite your irritating great-aunt. All you have to do is get down to a register office and sign a contract stating your commitment to each other, promising that you don’t intend to run off and leave your partner penniless, possibly holding the baby too.

Most cohabitees are happy enough to sign a contract for their flat or mobile phone, so why be so shy about signing a marriage contract? I’m not for wagging a stick at the sinful, but it is quite right that the law makes life difficult for partners not prepared to sign on the dotted line.

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