1. University Department of Haematology, Manchester Royal Infirmary, Manchester,
2. Department of Haematology, Royal Infirmary of Edinburgh, Edinburgh,
3. University Department of Medicine, Glasgow Royal Infirmary, Glasgow,
4. Department of Haematology, Royal Victorial Hospital, Belfast,
5. Medical Statistics Unit, University of Edinburgh Medical School, Edinburgh,
6. Haemophilia Centre, Royal Free Hospital and Medical School, London