You wouldn’t believe why my grandson doubts my sanity. ‘What did you do in the war, granddad?’ I looked down at my grandson, about to snap, ‘I’m only 68, not 98!’ and then realised, to an eight-year-old, anyone passed middle age must be ancient and had to have fought at Trafalgar. His question, I suppose, arose from all the news about Dunkirk on the television. The end of…