I t was the evening before my 40th birthday – a freezing cold night in March – and I was travelling across London to meet some old school friends for dinner. As I walked down the stairs into the tube station, I spotted a few teens leaning over the balustrade above me. I thought nothing of it; teens hanging about aimlessly is as classic a combination as Archers and lemonade. That was, until they each threw a few KFC paper cups’ worth of icy water over my head.

I noticed it in slow-motion and, at first, kept walking. Then I realised that my hair was wet and so was my back. Without thinking, I ran back up the stairs and followed the teens, who were marching off down the main road. People on the street were watching me, obviously intrigued to see what I was going to do. What was I going to do? A few people looked at me with pity and pointed me in the right direction.

When I caught up with the teenagers, they pretended it wasn’t them.…