Dyslexia, medically recognised tor 80 years, is the inability to read and write in children of normal to high intelligence. Ten per cent of our schoolchildren have trouble learning to read and write. But the Department of Education does not accept the existence of dyslexia, so how many of these slow learners are dyslexic is arguable. Michael Dean examines the controversy and reports from the only dyslexia clinic run entirely by the Health Service, at St Bartholomew's Hospital in London. He follows the fight for help for just two children: Adrian, aged 8, from Norfolk, and Judith, aged 6, from Berkshire.