‘Why did I cheat on my husband, even though I love him? I think some kind of recklessness took over,’ says Rosie*, a 44- year-old mother of three. ‘I was bored rigid with being sensible, and I wanted to feel that there was more to life than chasing the children about their homework.’

Rosie, a successful lawyer, had been married to fellow lawyer Stephen* for 17 years before she cheated on him last year with a man who runs a local Italian restaurant.

‘I’d been there with Stephen loads of times. He was attractive, maybe a year or two younger than me, and we’d always mildly flirted. One night, I went to his restaurant with my girlfriends and he bought us a drink then sat at our table, talking rubbish and trying to impress us. I went to the toilet, he followed me, we starting kissing and I still can’t quite believe what I did. Even a teenager wouldn’t do that.’

The sex was over in seconds but the thrill, shot through with profound guilt, remained. ‘It’s a cliché and of course it was wrong, but I felt more alive,’ says Rosie. ‘But then, after a couple of days, when I’d come down from my high, I thought, “What the hell have I done?” When I think about it now, I feel sick.’