1. York Trials Unit, Department of Health Sciences, University of York, York, UK
2. Department of Health Sciences, University of York, York, UK
3. Addictions Department, Institute of Psychiatry, London, UK
4. Birmingham and Solihull Mental Health NHS Foundation Trust, Birmingham, UK
5. School of Psychology, University of Birmingham, Birmingham, UK
6. Independent Research Consultant, London, UK
7. Independent Research Consultant, Bristol, UK
8. Birmingham Children’s Hospital, Birmingham, UK
9. Northumberland, Tyne and Wear NHS Foundation Trust, Newcastle upon Tyne, UK
10. North of Tyne Community Children and Young People’s Services, Northgate Hospital, Morpeth, UK