1. Department of Surgery, Salford Royal Hospital, Salford, UK
2. Department of Surgery, St Paul’s Hospital and University of British Columbia, Vancouver, British Columbia, Canada
3. Department of Surgery, Hammersmith Hospital, Imperial College Healthcare NHS Trust, London, UK
4. Department of Surgery, Nottingham University Hospitals NHS Trust, Nottingham, UK
5. Department of Surgery, Aberdeen Royal Infirmary, Aberdeen, UK