Felicity Mayer1, Debra Bick2, Cath Taylor3. 1. East London NHS Foundation Trust, City & Hackney Centre for Mental Health. Electronic address: felicity.mayer@nhs.net. 2. Warwick Clinical Trials Unit, University of Warwick & University Hospitals Coventry and Warwickshire. Electronic address: debra.bick@warwick.ac.uk. 3. School of Health Sciences, University of Surrey. Electronic address: cath.taylor@surrey.ac.uk.