Stephanie Flanders, former BBC economics editor, has a very personal interest in the battle to beat polio. Her father, Michael Flanders, one half of the world-famous singing duo of the 50s and 60s, Flanders and Swann, was paralysed by the infection when he was 21. He used a wheelchair for the rest of his life, and died early at 53 through complications caused by the disease. St...