Many nightclubs from this era were very loud and very dark. Plus some of the best ones were incredibly crowded. To begin with, I could seldom get back far enough to get people into frame from head to foot and when I could, people would be constantly walking in front of me all the time. Then I bought a 24-mm lens and only had to be four or five feet away.

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.

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.

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.

Things are very different now because a lot of those little clubs don't exist. In Soho for instance, where nearly half my nightlife photographs were taken, it's rapidly changing. There isn't the same after dark frisson of excitement about the place any more.

Only a very small proportion of us take those excesses with us into later life. In the age before everyone had a camera, it was worthwhile, in my opinion, to record those excesses. Sometimes, many times actually, the young people I photographed were only dressed that way for one night; that one night that they got snapped by me.

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.