Don’t get me wrong. There was nothing – well, nasty, about what I did. You know what I mean by that, I’m sure I don’t have to go into details. I’m far from being some sort of pervert, I can tell you. In fact, I err rather on the side of too much moral strictness. Nor am I one of those lonely, deprived men. I’m happily married and the father of a little boy, I’m six feet tall, not bad-looking and, I assure you, entirely physically and mentally normal.

Of course I’ve tried to analyse myself and discover my motives. Was my hobby ever any more than an antidote to boredom? By anyone’s standards the life I lead would be classed as pretty dull, selling tickets and answering passengers’ queries at Anglo-Mercian Airways terminal, living in a semi in Muswell Hill, going to tea with my mother-in-law on Sundays and having an annual fortnight in a holiday flat in South Devon. I got married very young. Adventure wasn’t exactly a conspicuous feature of my existence. The biggest thing that happened to me was when we thought one of our charters had been hi-jacked in Greece, and that turned out to be a false alarm.

My wife is a nervous sort of girl. Mind you, she has cause to be, living where we do close to Highgate Wood and Queens Wood. A woman takes her life in her hands, walking alone in those places. Carol used to regale me with stories – well, she still does.

‘At twenty past five in the afternoon! It was still broad daylight. He raped her and cut her in the face, she had to have seventeen stitches in her face and neck.’

She doesn’t drive and if she comes home from anywhere after dark I always go down to the bus stop to meet her. She won’t even walk along the Muswell Hill Road because of the woods on either side.

‘If you see a man on his own in a place like that you naturally ask yourself what he’s doing there, don’t you? A young man, just walking aimlessly about. It’s not as if he had a dog with him. It makes your whole body go tense and you get a sort of awful crawling sensation all over you. If you didn’t come and meet me I don’t think I’d go out at all.’

Was it that which gave me the idea? At any rate it made me think about women and fear. Things are quite different for a man, he never thinks about being afraid of being in dark or lonely places. I’m sure I never have and therefore, until I got all this from Carol, I never considered how important this business of being scared when out alone might be to them. When I came to understand it gave me a funny feeling of excitement.

And then I actually frightened a woman myself – by chance. My usual way of going to work is to cut through Queens Wood to Highgate tube station and take the Northern Line down into London. When the weather is very bad I go to the station by bus but most of the time I walk there and back and the way through the wood is a considerable short cut. I was coming back through the wood at about six one evening in March. It was dusk, growing dark. The lamps, each a good distance apart from each other, which light the paths, were lit, but I often think these give the place a rather more bleak and sinister appearance than if it were quite dark. You leave a light behind you and walk along a dim shadowy avenue towards the next lamp which gleams faintly some hundred yards ahead. And no sooner is it reached, an acid yellow glow among the bare branches, than you leave it behind again to negotiate the next dark stretch. I thought about how it must be to be a woman walking through the wood and, yes, I gloried in my maleness and my freedom from fear.