"I AM NOT a man-eating bigamist," Hayley Bates told reporters outside Portsmouth Crown Court on Wednesday. Clearly what she meant was that she was some other form of bigamist as opposed to a man-eating one, since she had just received a three-month suspended sentence for perjury, after failing to reveal that she was already married when she wed Stephen Perry, a sailor on the Royal yacht Britannia. Indeed, she had been married for more than two years to Andrew Bates, who was also formerly a sailor on Britannia and is now a stoker on HMS Quorn.

Mrs Bates considers herself more of an accidental bigamist than a man- eating one, claiming that she "genuinely believed" she was divorced. Nevertheless, the case raises a couple of interesting questions. For instance, why has the Navy begun naming its ships after vegetarian meat substitutes? And more pertinently, how many different sorts of bigamist are there? Study recent court cases and you quickly realise that the practice is far more common than one might imagine in an age when increasing numbers of couples choose to live together and raise a family without ever troubling the local registrar. The Archbishop of Canterbury would no doubt be pleased to see that there is still a significant body of individuals who apparently believe so firmly in marriage that they're willing to keep more than one on the go at the same time.

In fact, idleness seems to be the key in most cases. "I think one of the main reasons people commit bigamy is probably because it's easier to get married than it is to get un-married," says Dr Glenn Wilson, a psychologist at the Institute of Psychiatry in London. "Very often the original marriage has collapsed long ago. They've separated and lost contact with their original spouse and maybe they think it's easier to go ahead and get married and nobody will notice that they've been married once before."

Perhaps the record-breaker in this category in recent times has been Pat Hinton, who managed to commit bigamy at four of her 10 weddings and served a year in prison as a result. She claimed she was "just looking for love and security". Her 10 husbands included six soldiers, although she has now been happily married for several years to a telecommunications engineer.

Then there are further bigamy sub-groups, and these illustrate a difference between the sexes. "Male bigamy is more likely to be sexually motivated, a form of sexual exploitation," says Dr Wilson. "You'll find a man operating two families in parallel and shuffling backwards and forwards between the two. It's a manifestation of a particularly male tendency to be promiscuous. It's just that he's married the second one because he figured that it would take marriage to catch her or keep her.

"Female bigamy is more likely to be one of two things. Either it's an addiction to the ritual of marriage, which is a big turn-on to women, the idea of getting dressed up in your finery and exchanging all those vows and rings and so on. Or else it's a financial exploitation, getting a string of husbands and getting money off all of them."

The case of Barbara Fruin, who was given two years' probation last June after admitting two charges of bigamy, seems to be an example of the latter. Fruin had claimed: "I only wanted to be loved. I'm blind when it comes to men and can't help falling for a bit of attention." However, the debt- ridden men she had deceived put a somewhat less romantic slant on matters.

And finally there's the forgetful bigamist. According to Dr Wilson, there's an extreme condition called "fugue" where a person can simply up sticks and disappear, with apparently no memory of their former life and family. Leslie Knott was jailed for six months at the beginning of the year despite claiming that he had no record whatsoever of his first marriage and "believed at the time he was in Ipswich".

I think I know the feeling.