You notice someone at a window, at odd times of the day, and you realise they have been looking at you, and it does build up a sense of threat and vulnerability.
The first time it happened, OK, someone happens to be glancing out of his window, I would look away. At first he would look away, but he became quite brazen, and only I would look away. On the sixth occasion you realise there is an intensity of gaze, and really it is a form of terrorism. If you haven't experienced it, it probably sounds almost banal - it is difficult to convey the malevolence you can sense.
I felt violated. My peace of mind, my space, my freedom of action were violated. My work as a Russian translator was solitary, and working from home I was easy prey to this kind of thing.
It was my first flat, it was a lovely flat. But it was like I was not allowed to exist there, and I had to start drawing curtains.
I often had the curtains drawn in the daytime, which meant natural light was not coming into the flat, which was completely unnatural.
The summer of 1988 was a disgustingly hot summer, it was sweltering, and I found I was unable to sleep with my window open. And why should any citizen not be allowed to sleep with his or her window open? And that kind of constriction and containment I began bitterly to resent.
And I felt a sort of self-disgust, because fear is in many ways a shameful emotion.
At the same time I thought, why should I be afraid of him? Why isn't he afraid of me? Why does he not keep his curtains drawn? Doesn't it occur to him that I could go into his window?
Suddenly, the fear became rage, and one day I woke up and I literally wanted to kill him. I could visualise myself killing this man, and it was the most wonderful, electrifying feeling I had ever had in my life.
It was such a sweet thought, I would say a liberating fantasy, because women do not think in violent terms - it is not natural for us, we internalise all our rage and aggression, we get depressed and take Valium.
Suddenly, I had confidence and self-belief because I was actually able to imagine doing the unimaginable.
It was like watching a video in my head. I was going into enemy territory, like a commando raid. I would get dressed in my flat in the middle of the night, put on a Balaclava, tool up with a hammer, and then go across the gardens, which were littered with debris, then up his fire escape - he was on the second floor - and ease open his sash window, and climb in.
Then I imagined going into his bedroom where he would be sleeping: relaxed, secure. Suddenly, he wakes up, and the woman he's been watching, the woman he's been tormenting and hounding is standing by his bed with a hammer. I would hit him on the head, killing him.
It's extreme brutality, but abused people become abusers, people who have been violated become violent . . .
And I must admit it was very enjoyable imagining this type of act, it was liberating, like a peasant imagining sticking a pitchfork into the landlord.
It is threatening if a man stares at a woman, uninvited attention is harassment. Men must understand . . . this is an offensive act.
Helen Zahavi's first novel, 'Dirty Weekend', is published by Flamingo.