 From 1982 to 2008 he was Consultant Psychiatrist for the South London and the Maudsley NHS Foundation Trust and from 1999 to 2008 he held a Chair in Psychiatry at the Health Service and Population Research Department, at the Institute of Psychiatry, King's College London.His research has centered on the psychiatric ward environments, community psychiatry and the mental health of people with intellectual disabilities.He led the research programme in one of the first community mental health centres in the UK and played an important role in the development of the first community based mental health service in the UK for people with intellectual disabilities.