APPARENTLY, PEOPLE with dyslexia or autism make good engineers. Sounds like the sort of thing parents might have heard at the school open day, before anyone really acknowledged what dyslexia or autism were and how these conditions affected people. Can't read or write, but can drive a tractor. Work hard and one day you might even be able to design one. Alan Turing - the man whose work paved the way for the modern computer, the Second World War codebreaker and the all-round genius - was dyslexic too. Well, allegedly.But not according to Sir John Dermot Turing, Alan's nephew and a trustee of Bletchley Park, where the codebreakers broke Hitler's Enigma cipher and read secret communications between the Nazi leaders and their naval and airforce commanders. "Never heard of nor seen any evidence of Alan having been dyslexic," he says.