Melanie McDonagh: Look, if you insist on four wives, I insist on four husbands

The interesting subject of polygamy got an airing last week on Radio 4, courtesy of Inside the Harem, a programme presented by Shagufta Yaqub, the former editor of a Muslim paper, who encountered the phenomenon when a female reader got in touch to get help finding a second wife for her husband. The practice, she says, is unexpectedly widespread in Muslim Britain, though for obvious reasons no concrete figures are available.

Funnily enough, this is an aspect of Muslim identity that multiculturalists have yet to champion with any real enthusiasm, though perhaps Trevor Phillips may yet rise to the challenge.

I'm against it myself, although my only encounter with polygamy was in a benign form, in Buddhist Bhutan. There you sometimes find men marrying sisters, which has the advantage that you get a plurality of spouses - and, as the old gag goes, the plural of spouse is spice - but only one set of parents-in-law. Indeed, I seem to recall that the king of Bhutan had married an entire family of sisters, except for one that got away. It all depends, I suppose, on how well you get on with your siblings.

But at least in Bhutan you can find the practice cutting both ways. There was also polyandry among the Tibetan community, or a plurality of husbands. I think the principle is to prevent the division of family property.

One Tibetan woman I met, an inn-keeper, had married four brothers. One of them was the cook, another did the cleaning, the third minded the bar and the fourth appeared to do nothing at all. The children called the eldest brother father and the others uncle, regardless of which was the progenitor. It was a model of harmonious family life.

It's a little odd that Britain, which has abandoned so much of the Christianity that once informed its laws and sensibilities, should stick so stubbornly with monogamous marriage, or at least the principle that you should have one wife at a time. Mainstream British Muslims are not seeking to be allowed in law to have more than one wife, though it's quite possible that the minority who engage in de facto polygamy now may eventually wish to have the practice put on a legal footing as it is in a number of Islamic states. In terms of human rights legislation, they could argue that their right to a family life shouldn't be framed by Christian norms. They could also argue that it is an expression of religious identity.

Mohamed himself had more than a dozen wives, although his first marriage, to a woman called Khadijah, was both monogamous and rather modern, in that she was about 20 years older than him, and richer.

His marriages after her death were variously motivated - some for reasons of political alliance, others for the protection of vulnerable widows, some of them elderly. One, controversially, was to his adopted son's wife. And of them all, his favourite was the youngest, Ayesha, whom he married when she was a very young girl.

Muslims, however, are limited to a maximum of four wives and only if they can treat them equally.

Shagufta Yaqub, in her programme, took the view when she got married that if the Koran permitted polygamy, it wasn't for her to veto it, so she left it out of the marriage contract, while making it clear that if her husband did bring another spouse home, she'd have something to say about the matter. But she cited heartening examples of first wives who (eventually) took the situation in good part.

I've never had much time for the idea that polygamy had much to recommend it to the women involved, ever since my first adolescent reading of the Kama Sutra, which is vulgarly known as a sex manual but contains useful tips for an older wife on how to subvert a younger one, and for younger wives on how to undermine older wives. It was a bleakly realistic picture of polygamy in practice.

We have rather few moral taboos left, but I should be glad if we kept our residual Christian prejudice in favour of having one wife at a time.

Perhaps we should consider the Irish approach, which is to oblige Muslims settling in the country to promise to take only one wife. But if we ever legalise polygamy in the interests of multiculturalism, it seems only fair that we should allow polyandry too.

Rowan Pelling is away