Policy responses to the tumult of the global financial crisis of 2007-9 prompt a consideration of the critical dimensions in specifying policy change. UK monetary policy between 2007 and 2009 is characterised by a remarkable degree of innovation yet counts as a 'normal' period of policy making under the Hall (1993) framework of policy change, the enduring workhorse of the comparative public policy field. This exposes its lack of conceptual refinement in describing significant but within paradigm policy change. This paper traces this failing to the notion of a policy paradigm, both its scale and the ideational mechanisms which bind policy change. The paper develops the UK monetary policy case to consider the potential of the recently-minted concept of a thermostatic policy institution for the development of Hall's framework; but finds analytical limitations in coping with significant policy spillovers. Suggestions are made to meet this important challenge for future research in policy studies on the specification of policy change.