I preferred that option, where my camera (and by proxy, me) could look them straight in the eye. The way they reacted to me was always interesting. Sometimes hard young men would reveal vulnerability and a softer side. In the case of teenage girls, I often got a fascinating glimpse of the woman inside.

I went from being an underpaid ad man to quite a successful photographer in a very short time. Success breeds confidence and as soon as I got properly confident, I developed my own style. After that I never looked back.

Nowadays everyone has a camera and the Internet means everything is instantly accessible. Unlike some photographers, I don't see this as a problem. If anything interesting happens in the world today, there will be someone around to record it.

The reason why so many of my photographs in the book were taken in stairwells and corridors was that that was the only bit of spare space available and, in some cases, the only place where there was enough light to see anything. Even then, it was often so dark that I couldn't tell which gender my subject was (not that I particularly cared) and too dark, before the era of autofocus, to focus. I had to find a light (or carry a torch) and pre-focus.

When I gave up my office job and became a full-time professional photographer, my fortunes certainly improved markedly. We moved away from the council estate into our own house and for the first time in my life, I had a little spare money.

In the age of social media, you have the selfie and some people - not always young people - seem obsessed with showing the world what their face looks like almost every day. Just like some people are obsessed with showing the world what their dinner looks like. It's beyond my understanding to be honest.

When I was starting, I was very much influenced by the straight up, eyes to camera style of August Sander. He is really the only one. Had I known then the work of people like Ken Russell, Vivian Maier, Helen Levitt, and Steven Berkoff, they would undoubtedly have influenced me too.