Critical care services are atypical in the wide heterogeneity of their patients. This is in part a reflection of the way in which these services have evolved. The progress of intensive care in the UK has been described as ‘haphazard’, consisting of ‘largely unplanned and unevaluated’ developments that occurred in reaction to changes in surgical and medical practice. There has been debate about the configuration of critical care services, fuelled by a perception that there are not enough beds in some parts of the country and that existing beds are not in the right places. During the late 1990s, the NHS Executive established a National Expert Group to review adult critical care services in the UK and to produce a national Framework for future organisation and care delivery. As a result, in May 2000 a critical care modernisation plan was announced.