1 Research Department of Clinical, Educational & Health Psychology, University College London, London, UK. Electronic address: amanda.williams@ucl.ac.uk.
2 Cochrane Pain, Palliative and Supportive Care Review Group, Oxford University Hospitals, Oxford, UK.
3 Court Road, Newton Ferrers, Plymouth, UK.
4 School of Natural and Environmental Sciences, University of Newcastle upon Tyne, Newcastle, UK.
5 Centre for Pain Research, University of Bath, Claverton Down, Bath, UK.
6 Department of Health Sciences, Centre for Health and Wellbeing Across the Lifecourse, Brunel University London, Uxbridge, UK.