1. Imperial College School of Medicine, Imperial College London, London SW7 2AZ, UK
2. The Devonshire Lodge Practice, 12A Abbotsbury Gardens, Eastcote, London HA5 1TG, UK
3. King's College London, Strand Campus, London WC2R 2LS, UK
4. The Hillingdon Hospital, Uxbridge, London UB8 3NN, UK