There has long been a disparity between the practice and the neo-Diceyan doctrine of accountability in British central government. This article shows that the New Public Management (NPM), while not itself the root cause of such disparity, has nevertheless both exacerbated and further exposed existing fault-lines. This much is evident from an examination of NPM’s theoretical bearings and from brief case studies of the Child Protection Agency and the Prison Service. Reflecting broad and deep-seated forces, the NPM is unlikely to disappear. Thus although there are certain attractions in retaining neo-Diceyan assumptions, it may be more appropriate to reconstruct the formal doctrine. Drawing upon Spiro’s notion of ‘multicentric’ accountability and within the context of calls for wider constitutional reform, the article sketches the basis for a new doctrine, having regard to relevant moralities and practicalities.