He had been diagnosed as suffering from this condition which does cause intense pain on one side of the head and is experienced by just one per cent of the population.
Radcliffe tells The Independent on Sunday,
“I was in the middle of these weird things called ‘cluster headaches’. It’s very rare evidently, but it’s exceptionally painful. It makes a migraine look quite tame. At the time I thought I was being a wuss (coward). I was taking 12 (strong painkillers) a day and going, ‘Why do I still have a headache?’”