Primary medical care in the UK is based on an encounter system with a general practitioner (GP). The GP is usually the first point of contact with the National Health Service (NHS) and controls access to secondary care via the referral system, acting as a gatekeeper to secondary care. An international comparison of primary care suggested that the gatekeeper system may result in better levels of health and lower costs (Starfield, 1994). However, referral by a GP is not the only mode of entry into secondary care. Other routes include emergency admissions and patient self-referral through accident and emergency departments.