Sir Roy Strong was preparing to give a speech at Hereford Cathedral when he realised he felt so unwell that he needed to sit down and gather his strength. This had nothing to do with nerves.

A seasoned writer and broadcaster, not to mention former director of the Victoria & Albert Museum (1973-1987) and National Portrait Gallery (1967-73), he was undaunted by public speaking. No, this was far more serious – he felt dizzy, listless and extremely tired.

‘I thought I had summer influenza, but a week later, despite having taken over-the-counter cold remedies, I realised this thing wasn’t going away,’ says Sir Roy, 76, speaking at his Herefordshire home.

‘I arranged to see my GP and after checking he said, “You have a pulse rate of 160 and I need to get you to the County Hospital in Hereford within the hour.”’...