Louise M Howard1, Fiona Challacombe2. 1. Health Service and Population Research Department, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE5 8AF, UK; South London and Maudsley NHS Foundation Trust, London, UK. Electronic address: louise.howard@kcl.ac.uk. 2. Health Service and Population Research Department, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE5 8AF, UK; South London and Maudsley NHS Foundation Trust, London, UK.