Dr. Tim Williams has known people with autism spectrum disorder since childhood. When he started his professional work as a clinical psychologist, he worked in a small residential hospital for children with autism and severe learning difficulties. His doctoral thesis was on teaching methods for children with autism, and following the closure of the hospital he was asked to set up a community based assessment and intervention service. He retired from that post in October 2010 and now works part time for a school for children with autism and learning difficulties, for the National Health Service and for the University of Reading. He has published more than forty peer reviewed papers on autism, behaviour problems and obsessive compulsive disorder.