I must have been mad. Well, that's what I say now but, at the time, it all seemed perfectly natural - anyway, you be the judge.

I live in one of those tree-lined streets that abound in our part of West London. Row upon row of large Victorian terrace houses; each absolutely identical to its neighbours and each a mirror image of the house opposite - the only distinguishing feature being the colour of the front door. One evening, towards the end of last June, I was returning from the office when, as I rounded the corner of our road, I saw ahead of me a girl being set upon by three loutish teenage boys. On reflection, I suppose it would have been wiser to stop and think about how a forty year old should sensibly behave in such circumstances but, obeying my natural instincts, I immediately rushed in to break up their attack. Presumably, because of their obvious enjoyment at trying to strip the girl of her blouse and skirt they were unaware of my approach so, when I slammed my fist hard into the kidneys of the nearest boy, he was apparently so flabbergasted that he let go of the girl and turned to see from where this new onslaught originated. So incensed was I at their behaviour that, without waiting for further reaction from the boy himself, I kicked him hard in the crotch. He yelped in agony and fell to the ground writhing in pain. The other two boys, sensing that their mate was the victim of an outside attack, immediately let go of the girl and, without a backward glance, took off down the street.

Helping the sobbing girl to her feet, I retrieved her handbag from the pavement and proffered my handkerchief so that she could wipe her face. I stood holding her for a few moments until I could see that the tears had subsided and she had regained sufficient control to stand up by herself and straighten her clothes.

'Where do you live?' I asked when she seemed capable of speaking.

'Number 15' she replied. So, after a quick check that the boy on the ground was still alive, I took her arm and led her down the street until she was by her door.

'I'm just up at number 22' I told her, more by way of something to say than feeling she needed to know where I lived but, by then, she was obviously much more relaxed and clearly able to talk. She explained that she was an au pair girl, over in England from her home in Malmo, Sweden, and for the last five months had been working for a young family here in Ealing.

'Well, are you OK now', I enquired feeling that my Sir Galahad duties were fast coming to an end and it was time I went on.

'Yes, fine. Thank you very much,' I noticed that her English showed little sign of a Scandinavian accent and, on that final sounding exchange; she produced a key from her bag and went inside.

I thought little more about the incident, indeed so little that I didn't even mention it to my wife that evening but it was to be brought back sharply to me a few evenings later.

I was in our sitting room reading the evening paper when the doorbell went. Going to the front door it was none other than that self-same Swedish au pair girl. Standing there in a light blue cotton dress and sandals, her fair hair bathed in the evening sunshine, I was much more aware of her than on our first encounter and I couldn't help but think to myself what an attractive girl she was, more particularly as she was now smiling. Of course, she looked much more assured than when we first met but I suspected for all that she was still just a young girl in her late teens or 20 at the most.

'I've come to say thank you' she announced.

I smiled back at her but, being caught slightly on the hop, I was a bit unsure as to how to proceed. 'There was no need for that Miss . . er . . . I'm sorry I don't even know your name'.

'Well, Elsbet, as I said, there was no need for thanks but, as you've been kind enough to come round, why don't you come in?' and, with that, I led her down the hallway and into the sitting room.

'Can I get you something? A coffee? Tea? A drink perhaps?' I walked towards the drinks tray on the far side of the room thinking that, even if she didn't want one, I could certainly do with something.

When I turned round I got the shock of my life. There was Elsbet standing facing me stark naked with her dress lying around her ankles.

'I know how to say thank you to a man', she explained stepping away from her dress and moving towards me.

It was at that point that I realised I was in for trouble. 'I'm sure you do, my dear, but there's really no need for you to do that. I was delighted to have been able to help you but wouldn't it best be left at that.' I was anxious not to hurt the poor girl's feelings but equally well aware of what my wife's reaction would be was she to come in and find a nubile young girl standing naked in our sitting room.

'I have made many men happy' Elsbet went on.

'Elsbet, I'm not sure how to say this without it sounding silly but I am a married man old enough to be your father. Now please put your dress on again and let's call it a day'.

'Perhaps you do not like girls' Elsbet was clearly taken aback by my rejection.

'Elsbet, I love girls. I just don't happen to think that what you are suggesting is a good idea', and, with that, I went to the middle of the room and picked up her dress. 'Why don't you put your dress back on and we can part as friends', and, without waiting for a reply, I started to pull the dress over her head.

'What the bloody hell's going on in my sitting room?' My wife's voice boomed across the room and, peering round Elsbet's head I saw her framed in the doorway. Obviously in my preoccupation with the girl and the dress I had failed to hear the front door open.

'Hello Darling', I said trying to make my tone as nonchalant as possible. 'Don't worry. This is not at all what it looks like. Our friend here came round to say thank you because I had helped her the other day and, well, they have a rather different way of saying thank you in Sweden that's all. But it's nothing for you to be upset about'. I wish the truth hadn't sounded quite as foolish as I was feeling just at that moment.

'Saying thank you in any language doesn't require you to wrap yourself round the body of a young girl as you take her dress off.'

'I wasn't taking her dress off, Darling. I was helping her to put it back on.'

By now Elsbet must have realised that she had created something of an uneasy domestic situation and was obviously anxious to make amends. 'Please Mrs, it was all my fault. I wanted to make your husband happy but I am thinking perhaps you make him happy yourself.'

'What I do or do not do for my husband is no business of yours, miss . . . whatever your name is.

'Elsbet', I chimed in,' she lives at number 15'.

That was quite the wrong thing to say for, far from pacifying my wife, providing the missing information was clearly a tactical error. 'If I was you,' my wife retorted, 'I would keep very quiet. You seem to know far more about this young girl than is good for you' and, turning to Elsbet added, 'Now, put your clothes back on and get yourself out of this house.'

Elsbet needed no second bidding and slipping her dress back on, she scuttled from the room and out the front door.

'Let me explain. . . ' I began hoping to quieten my wife's concerns.

She interrupted without letting me finish, 'I don't want to hear another word from you. The best thing you can do now is to pour me a stiff drink and, when I've changed, take me out to a very expensive dinner where you can spend the whole evening grovelling'.

"Brief Encounter" by Dermot Hoare