[1] St Marks Hosp, Wolfson Unit Endoscopy, Harrow, Middx, England
[2] Univ London Imperial Coll Sci Technol & Med, St Marys Hosp, Dept Surg & Canc, London, England
[3] Queen Alexandra Hosp, Cosham, England
[4] Univ Wales Hosp, Cardiff CF4 4XW, S Glam, Wales
[5] New Cross Hosp, Wolverhampton, W Midlands, England
[6] Torbay Hosp, Torquay, England
[7] Leeds Gen Infirm, Leeds, W Yorkshire, England
[8] Univ Hosp N Tees, Stockton On Tees, England
[9] No Gen Hosp, Sheffield S5 7AU, S Yorkshire, England
[10] Gloucestershire Royal Hosp, Gloucester GL1 3NN, England