1. Trent Oesophago-Gastric Unit, Nottingham City Hospital Campus, Nottingham University Hospitals NHS Trust, Nottingham, UK
2. NELA Research Fellow, Royal College of Anaesthetists, London, UK
3. Clinical Effectiveness Unit, Royal College of Surgeons of England, London, UK
4. Department of Health Services Research and Policy, London School of Hygiene and Tropical Medicine, London, UK
5. Department of Surgery, Royal Lancaster Infirmary, University Hospitals of Morecambe Bay NHS Foundation Trust, Lancaster, UK
6. Colorectal Surgery Department, Salford Royal Hospitals NHS Trust, Salford, UK