When Edda, aged 18, arrived from eastern Europe, she seemed sweet and eager to please. Victor Osborne describes the horrors that followed
We've had an au pair who picked up our five-year-old and dropped him into the bath clothed when he wouldn't get undressed, then went to her room as if nothing unusual had happened. She was worse than the one who sent the children to school with sandwiches of raw bacon buttered on the outside, but not as wearing as the one who, during the Gulf War, became hysterically convinced that Saddam Hussein was going to bomb our suburban London house. Another clogged up the drains after bulimic binges, and one down the road had a roomful of photographs of her bonking different men.

None of them prepared me for the au pair from hell.

She didn't look it. Edda (not her real name) was two weeks short of her 19th birthday but looked 15. She had shoulder-length auburn hair and was shy but eager to please. She looked like a lost schoolgirl in need of a good meal and some decent clothes to replace the shapeless and functional eastern European ones that she arrived in.

The first few weeks went well. She loved English food and ceased to be waif-like. She wasn't homesick, she was fascinated by the English way of life and sense of humour. She seemed a sweet and pleasant girl in a thoroughly ordinary way.

But there were a few things that began to worry us almost from the start. Edda couldn't organise herself to do things when they were supposed to be done, or in a proper way. The dining-room furniture became festooned with damp washing because she kept forgetting to use the drier. She always left the back doors open after she used them and, though I told her a dozen times that this was the preferred route for burglars and demonstrated how to turn the keys, she wouldn't lock them.

Suggestions for doing things differently were initially disregarded but increasingly taken by her as personal criticism. She always had a ready reason why she couldn't do things our way, and if requests were repeatedshe took on a hunted, persecuted expression.

I noticed that we seemed to be running low on crockery at about the time that my wife began to complain, to me, about the state of Edda's room. Mugs and plates with congealed food were piling up in there. Dirty clothes were all over the floor.

But was Edda any more slovenly than the average teenager? The Home Office says that an au pair should be treated as a daughter, and while we vacillated between behaving like indulgent parents and laying down the law, events began to overtake us.

Edda was driving my nine-year-old son home from games when she hit a parked lorry. Though she hit it at low speed, in first gear, she didn't stop. What should have been a £100 dent in the wing turned into £1,500- worth of damage because she dragged the whole side of the car along the lorry. She never showed any concern about the accident, and she was upset only because she thought she would be sent home.

A few days later, without warning, Edda shaved her head completely. The children were stunned. So was I. She said it was a fashion statement. The smell of burning incense, or exotic herbs, leaked under her door.

Edda became increasingly withdrawn and preoccupied. On a Monday evening, a few hours after my wife had left for a week's business trip, she gave two weeks' notice. She said English culture was too strange, she didn't like being told what to do and she couldn't adapt to living in a family. Relief prevented me from asking how she ever thought she could have functioned as an au pair.

When I got home from work the next day, she had cleared her room and gone. She had brought my nine-year-old home from school and left, saying she was going for cigarettes. As it got dark and she didn't return, he became more and more frightened. He thought bad men were going to look through the windows, see he was alone and get him, so he went round closing curtains. He didn't use the phone in case "they" were listening, and he didn't put on any lights. If I had seen Edda after I saw that petrified little boy sitting with an unnatural stillness at the kitchen table, I don't know what I might have done.

He still finds her behaviour incomprehensible and won't mention her name any more. If anyone else mentions it, he says: "Who's she?" He is also worried all the time he's in a car that there'll be another accident.

Edda went back to Germany. She had been with us for six weeks. The more I think about her, the more I think we got off lightly. A friend has a 20-year-old Slovakian man as an au pair and says he's brilliant and we should try a man. We just might.