It is no secret that I have spent a large chunk of my life writing about the economist John Maynard Keynes. In 1973, a few months after my son Edward was born, he got a postcard from my mother-in-law. She clearly believed in encouraging early habits of reading. It was of Gwen Raverat’s famous watercolour of Keynes as a young man. “This is a gentleman whom you and Mummy and Daddy will soon grow to hate v. enormously I expect. He looks a bit furtive to me.” My son Edward is now 30.