In 1990 I was a junior doctor at the John Radcliffe Hospital in Oxford. I had just finished all my training as a medical student, and was starting my first year working on the wards. Roald Dahl was one of the patients. He was in his seventies, and had been in and out of hospital in the preceding few months with anaemia. He was being cared for by my boss, one of the country's most distinguished haematologists, Professor Sir David Weatherall. Dahl was becoming increasingly frail as the summer progressed, and Weatherall was doing all he could to determine the cause of the anaemia. I can remember the night I first met Dahl. I was on call that evening, and was told in the handover that the ‘great author’ had just been admitted for tests. As the doctor on call, I had to stay in the hospital overnight to complete any jobs left over from the day, give the night-time drugs and deal with any new problems that arose.

That night I had finished examining the patients, talking to relatives and taking blood samples. Things had quietened down. Rather than go and rest in the on-call room, I settled in front of the ward computer, and was busy writing up some research I had been doing the previous summer when as a medical student I went to study malaria in Africa. It must have been nearly midnight, and the lights were all down low when I became aware of this large figure wandering slowly up the ward, casting a great big shadow. I carried on tapping away at the keyboard, concentrating on my data. The restless patient walked past the nurses’ station where I was working, and a few moments later wandered back again. He must have come past three or four times, each time a little bit slower, peering over my shoulder, trying to see what I found so absorbing. Eventually he stopped.

‘What are you doing?’

It was a deep, booming voice. I looked up to see an enormous giant of a man towering over me. He was wearing a silk nightshirt, and was wrapped in a huge dressing gown.