Jeremy Nicholl: I’m 56, but I don’t feel like it. I bought my first camera when I was about 10 with some money I’d been given for my birthday. It seemed to me like a magic box. Point it at someone; click click click; post the film cassette to a chemist; a few days later photographs came back. Then a few years later I learned a real magic trick. Our school had an old darkroom that nobody used, so I missed classes I didn’t find interesting and went to the darkroom instead. There I learned that if I mixed some...