It was August1453. King Henry VI of England left his pregnant wife Margaret of Anjou at home and travelled from court to the West Country on a judicial visit. Stopping off at Clarendon Palace in Wiltshire the 31-year-old king was, “suddenly…taken and smitten with a frenzy and his wit and reason withdrawn”. What was the terrible and mysterious illness that struck down Henry VI who was a central figure in the Wars of the Roses?