'It's a peculiar kind of psychological torture. Someone is out to get you but you have no idea who or why'

I was 23 when it started. My boyfriend and I had just moved into a run-down Victorian gothic pile. We had been there only a week or two when we started getting silent phone calls about three times a week. The caller would stay on the phone, sometimes for half an hour at a time, never speaking. When we dialled 1471, the number was always barred. We assumed the calls were the work of a random crank and followed BT's advice: say nothing and put the receiver to one side until they hang up.

We thought our phantom caller was weird but funny until one night my mum rang, begging me to leave the house. She'd just taken a call from an unknown man who had whispered down the phone various ways he planned to harm me.

I was standing in the hallway trying to reassure her when I spotted that an envelope addressed to me had been shoved through the letterbox. Inside was a pornographic magazine. Suddenly the funny calls weren't funny any more.

Around 2.1 million people are stalked each year, according to the British Crime Survey, but 97% know the identity of their harasser, often an ex-partner or casual acquaintance. Those of us in the remaining 3% don't have to endure in-your-face harassment. What we do experience, however, is a peculiar kind of psychological torture. Someone is out to get you, but you have no idea who – or why.

It's like walking around with a blindfold on when there's someone dangerous close by. Everyone becomes a suspect. Your imagination tries to fill in the gaps and, as all good horror film directors know, leaving things to the imagination can make them more terrifying.

For the next seven years, my life became a clichéd thriller: silent calls in the night, obscene poems and packages of lingerie in the post, battery acid splashed over my car. Things would go quiet, sometimes for months, but each time I thought it was over, the phone would ring or another package would arrive.

I questioned every relationship: boyfriends, friends, colleagues. I felt watched all the time. My sister convinced me to carry a bottle of water everywhere in case the stalker decided to step it up and throw the acid in my face. I remember one night driving to a theatre in the next town to help a set-designer friend paint some scenery. I drove home late and had to park two roads away from my usual spot. By the next morning the stalker had found my car and covered it with paint, as if to say: I know exactly where you've been and what you've been doing.

The police were enthusiastic. The 1997 harassment act had just come in and they got to work tracing phone calls, installing surveillance cameras and panic buttons, and investigating suspects – but every inquiry drew a blank. The calls came from phone boxes across the city, there were no witnesses, no fingerprints, suspects had alibis and the stalker seemed to know about the cameras: he vandalised my car only when I had to park out of range. The police remained supportive but concluded that the stalker was unlikely to act out his threats. Their investigation petered out and I was not confident enough to press them.

I internalised the stigma that "nice" girls don't attract this sort of attention: I must have "asked for it". I analysed my own behaviour, searching for clues, but I was on good terms with my ex-boyfriends and knew none of them was responsible.

After each stalking episode, I pretended to be fine, concealing my feelings from everyone in case the stalker was a friend or acquaintance feeding off my distress. I could have felt degraded by it all but decided my best revenge – the only revenge available to me – was to remain as unaffected as possible. I did my best to sidestep the victim role the stalker was trying to pin on me.

The stalking finally stopped 10 years ago when I married and moved to another city. To this day, I don't know the identity of the person, or people, who devoted so much time and energy to trying to distress me. It is a bit like ploughing through a crime novel only to be denied the denouement of whodunnit by a few missing pages at the end.

I no longer need to know who or why. I'm no longer scared to be alone in the house. My experience could have left me paranoid, but it hasn't. Others haven't been so lucky.

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