It started with an innocent little piece in the Back Pages in February 2002. I had spent Christmas with friends in Langholm, Dumfriesshire. The previous year had seen the British farming industry and countryside scourged by foot and mouth disease, so the appearance once more of sheep on the Scottish hills was cause for rejoicing. At the same time, Dr Andrew Wakefield’s controversial suggestion of a link between MMR vaccine and childhood autism had blown immunisation targets out of the water, and everyone wanted to know whether little Leo Blair, the Prime Minister’s youngest child and aged 19 months at the time, had had his MMR1. The connection seemed, if not obvious, at least worth exploring.