When daddy's little girl grows up: I'd much prefer not to see it going on

How do fathers feel when their daughters start having sex? One man drove to the house of his 16-year-old daughter's boyfriend at 1am. Was she there, he wondered, and, if so, what were they doing? Looking up at the dark windows and feeling foolish, this confident businessman realised he hadn't a clue what to do next. What he wanted to do was smash down the door and drag the young man out. He realised then that his feelings stemmed not so much from parental concern as a deep, tearing-apart jealousy . . .

Jeremy King, 48, is a banker. His 17-year-old daughter, Eloise, is still at school.

It was becoming evident, because she's attractive and has an engaging personality, that my daughter was both attractive to and being attracted by boys. My wife took the line that as she was going to be sexually active sooner or later, it was better that it should happen in a controlled environment, that we should let them sleep together in our home rather than her having a sexual life in the back of a car.

I could see the logic, so in the end I agreed. But I wasn't happy. Inevitably I felt extremely critical of any boy my daughter was going out with, I felt they weren't up to her standards; that they were scruffy, long-haired no-hopers or, in one case, at least three years older and probably taking advantage of her.

Another aspect has been watching my daughter change from being a child, a schoolgirl, into a woman. Not just a woman, but an extremely attractive woman. I suppose I feel I have lost something. There's also resentment. This is a head-in-the-sand attitude, I know, but I would much prefer not to see it going on. I hate knowing that she'll come in with her boyfriend and they'll go upstairs and go to bed together. I find that very disturbing.

Yet, at the same time, it seems there just isn't any better solution. If it isn't taking place under my roof, it would be taking place somewhere else, possibly less safe, less salubrious. And at least she isn't out late at night, travelling from A to B, which is an extremely dangerous activity.

I'm left with all these very mixed feelings. I resent the fact that someone I'd regarded for so long purely as my daughter is suddenly in one's house behaving like a mature woman. She is my only daughter, after all. Had I other daughters, it might have been different. Fortunately, the relationship she's enjoying - if that's the right word - does appear to be stable and it's not affecting her examination results or her diligence at school. On balance, it's as good as one could expect - certainly it's better than a life of hidden promiscuity.

So why am I so rattled by the whole thing? I have to admit, I suppose, that I'm jealous - sexually jealous. It's almost inevitable that a couple who've been married for over 20 years should find the initial sparkle has gone out of the physical side of their relationship. And then suddenly, under one's roof, there is, um, sexual activity taking place - quite energetic, I should think - that doesn't involve yourself but does involve a girl who, until recently, was just seen as one's daughter, but who is now an attractive, sometimes exotically dressed young woman, with a boyfriend who's having the obvious advantage of it.

What makes it even more difficult for me is the fact that in the same way as I have suddenly begun seeing my daughter through different eyes - you know, as the active woman - she and my wife go clothes shopping together and inevitably, when discussing their purchases, the question of whether the boyfriend will like it comes into the equation. There's now an unanswered question in my mind: is there an additional reason for my wife favouring the cohabitation? I wouldn't ask her directly but I do wonder if, as a 40-plus woman, she's actually excited by the idea of an 18-year-old toy boy under her roof.

I think what I really feel is envy. But I expect masses of other 48-year-old married men fantasise about having a relationship with a 17-year-old girl. I don't set out to be a psychologist, but it's occurred to me that the start of my daughter's sexual activity has coincided with the male menopause - if there is such a thing. All I know is that I sense I'm on the cusp between the two halves of my life . . . and am experiencing a sudden and worrying degree of irresponsibility.

The names in this interview have been changed.