I am 61 years of age. I cycle to work every day, play badminton and tennis every week, and cycle or hill walk most weekends. I eat healthy food, have never smoked and drink on a moderate social scale. But one Sunday morning in September 2009, at the yachting marina of Portavadie on Loch Fyne in Scotland, I had what I thought was a stroke.

Prior events were normal. Having sailed from Faslane on the Clyde the previous morning, I had spent several hours at the helm in blustery conditions in the afternoon, followed by a sociable evening in the marina. Before turning in I tidied the loose ends on deck, and slept for a solid 7 h before a robust breakfast in preparation for a lively return trip. On paying a last visit to the marina facilities I became aware of numbness in my left leg as I stood at the urinal (T+0 min). I struggled to reach the wash basin where I realised that my arm was going the same way. I was becoming increasingly alarmed. My …