American writer Pamela Druckerman knows all the rules of infidelity. She spent three years studying adulterers, from Paris to Tokyo.

She discovered that the Japanese don't count it as infidelity if they've paid for it, and that the best thing that can happen to them in one of their famous sex clubs is 'oral sex without showering first'. She discovered that 40 per cent of Russians surveyed think affairs are 'not at all wrong' or 'not always wrong', and that upper-class Muscovites think affairs conducted at beach clubs do not compromise wedding vows one iota. She discovered that Indonesian women in extremely traditional Islamic marriages 'have affairs, and the reasons they give for them are exactly the same as the reasons my girlfriends in New York City gave: my husband doesn't listen to me, I need someone who'll make me feel smart and pretty again; my husband doesn't do that, but my boyfriend does ...' She discovered that on average the British cheat more than the Americans - and the French.

he had over 25 sexfriends!