My Greatest Mistake: Professor Sir David Weatherall molecular geneticist

It took a catalogue of mistakes on my part and a gorgeous series of cock-ups on behalf of the British Army which led me into my research field. When I qualified for medicine in the late Fifties, it was still in the days when you had to do National Service and I was invited to tell them where I would like to do it.

I was terrified of flying, terrified of fighting and petrified of snakes, so I volunteered to stay in the UK. The Army did the opposite, and three weeks later I found myself on a troop ship to Singapore.

Once there, I had to do six months surgery and six months medicine. At that stage I didn't have a clue about the way my career would go. I'd had visions of becoming a neurosurgeon and I began my surgery stint by attempting appendix operations. By the third one, I'd yet to find the appendix and by the end my surgical boss told me that on no account should I be let loose as a surgeon. I then moved on to the six-month period in medicine, and I told them that all my experience was in adult medicine. Within the week the British Army in their wisdom put me in charge of a children's ward.

A week or two later, a child of a Ghurka soldier appeared on the ward, who was profoundly anaemic and critically ill. The Army specialist had been through every disease in the book, but no diagnosis appeared. I did some work on the child's condition with a colleague and we came up with a diagnosis of Mediterranean anaemia. To have Mediterranean anaemia in a child who came from Nepal seemed incredible. So we ruled that out for a while, until I discovered a remarkable paper. We went back and, sure enough, the child did have the condition.

This was a big deal for a young doctor. We now know that it's one of the most common genetic diseases but, back then, this was most bizarre. We wrote a little paper, which was published in the British Medical Journal. I've worked on that disease ever since.