Everyone knows that love can be sudden, foolish and catastrophic. On the whole it’s better assembled gradually than experienced at once as a bolt from the blue, like the stigmata. Quite how love happens ‘just like that’ no one knows. It might be an ankle, the toss of a head, an imbecilic smile, or an equine laugh. Read as many romantic novels as you can and you’ll never discover the cause. Barbara Cartland, William Shakespeare, they were sensitive observers, but they weren’t true scientists.

Spontaneous hatred is equally inexplicable but we all experience it from time to time. Flowing from us or coming at us. It might be the licking a finger before the turning of a page. It might be a matter of table manners. It might, from a different perspective, be that imbecilic smile or that equine laugh. Sometimes it’s the tiniest, almost imperceptible thing.

I was the victim of it myself, the other day, a spontaneous burst of hatred coming in my direction on the tube between Ladbroke Grove and King’s Cross St Pancras. A man sitting opposite me glared at me in an alarming way as I took my seat, and he went on glaring, even when I wasn’t looking. I could sense it. He didn’t look like a terrorist bent on the indiscriminate taking of many lives, so I wasn’t inclined to reach for the emergency stop. No, it was my jib he didn’t like the cut of, and mine alone.

As far as I could tell, there was nothing odd about my jib. There never is. I was dragging a suitcase towards Luton Airport and my jib was the usual jeans and polo shirt. I caught his angry eye, and looked away, and then back again as we passed through Paddington, and Edgware Road and Baker Street, to see if he was still looking, and then I decided I wouldn’t look at him at all. The last time I looked, he raised a finger at me like this:

I was frightened, to tell the truth, just a little, but I couldn’t see that he was any danger. The previous evening a young man had run amok in Russell Square leaving an American woman dead and several people injured, so I was alert to the dangers of insane behaviour in a public place and ready to run should he lunge.

At Great Portland Street he tottered to his feet and lurched towards the exit, and it was only then that I realised he was completely drunk. I heard another passenger commenting on the smell of drink as he stumbled from the train. Even so, why did he pick on me?

Drunk or sober, instant dislike is disturbing. My father used to say, ‘I don’t like the cut of his jib’ when he took against someone he didn’t know. He used to say it quite often, and, to give credit where it’s due, he was often right about the people whose jibs he took against, and I often ended up taking against them too. But I never remember him raising a finger to make his point.

I looked up ‘cut of his jib.’ It’s a nautical term, apparently, from the early 19th century, the jib being the forward sail that indicated a ship’s nationality. So a ship with the wrong cut of jib is an enemy one best avoided. Wear your jib carefully.