[1] Harold Wood Hosp, Romford, Essex, England
[2] William Harvey Hosp, Head & Neck Directorate, Ashford, Kent, England
[3] Dept Otolaryngol Head & Neck Surg, London, England
[4] Guys Hosp, London SE1 9RT, England
[5] Royal Natl Throat Nose & Ear Hosp, Dept ENT Head & Neck Surg, London WC1X 8DA, England