[1] Univ Cambridge, Dept Psychiat, Cambridge Intellectual & Dev Disabil Res Grp, Cambridge, England
[2] Northgate & Prudhoe NHS Trust, Psychol Therapies & Res, Newcastle Upon Tyne, Tyne & Wear, England
[3] Northumbria Univ, Newcastle Upon Tyne NE1 8ST, Tyne & Wear, England
[4] Northgate & Prudhoe NHS Trust, Psychiat, Newcastle Upon Tyne, Tyne & Wear, England
[5] Tayside Primary Care Trust, Clin Psychol Serv, Dundee, Scotland
[6] Univ Abertay, Dept Psychol, Dundee, Scotland
[7] Nottinghamshire Healthcare NHS Trust, Psychiat, Nottingham, England
[8] Rampton Hosp, Nottingham, England