Abstract
The concept of supply and demand is well established within the health economy of the UK. However, complex health and social care needs, associated with an ageing population, pose a novel challenge to NHS resources and, in particular, its workforce. Although existing strategies adopt a more linear approach to clinical activity and workforce demands, the Workforce Repository and Planning Tool process draws upon the principles of 'realist' data evaluation to combine -empirical evidence, practical experience and clinical theory to offer transformation strategies for an NHS workforce that is fit for purpose and its patients.