1. Therapies Department, Royal National Orthopaedic Hospital NHS Trust, London, UK
2. Population Health Research Institute, St. George’s University of London, London, UK
3. Centre for Behaviour Change, Department of Clinical, Educational and Health Psychology, University College London, London, UK
4. Victor Horsley Department of Neurosurgery, University College London Hospitals NHS Foundation Trust, London, UK
5. Department of Clinical Health Psychology, Royal National Orthopaedic Hospital NHS Trust, London, UK
6. Institute of Social Marketing and Health, University of Stirling, Stirling, UK