A continuing programme of NPM reforms, grounded in quasi-market modes of governance and private sector best practice, have been applied to English NHS hospitals over the last thirty years in response to concerns about their performance efficiency and accountability. However, in the transition to market modes of governance, the retention of hierarchical features gave rise to a multi-layering of accountability. From 2001-02 balanced scorecard inspired performance measurement systems (PMS), were introduced into the NHS, aimed at improving service standards through improved cost efficiency. Study 1 in this thesis finds that, in this context, the relationship between service standards and cost efficiency is positive and that, consistent with it being a more effective PMS, this was stronger for the ‘Annual Health Check’, a PMS characterised by features aimed at reducing manipulation, than the Star ratings, its predecessor. The approach to the manipulation of financial breakeven, a key accountability measure, was however more relaxed, particularly when service standards were under threat. The system of ‘financial support’ had its roots in previous hierarchical relationships and acted to shift revenue across the NHS in order to allow Trusts in financial difficulty to meet their financial objectives without damaging service standards. These transfers, which were effected through the revenue account, were generally reversed out in future years with the result that financial support accelerated revenue recognition in Trusts receiving it. In Study 2, the receipt of financial support by Trusts in financial difficulty was found to be associated with an improvement in service standards and in future financial performance but, in an increasingly demanding performance regime and multi-layered accountability, evidence was also found of opportunistic exploitation of the system. Financial support had a considerable impact on the accountability of both NHS Trusts and the wider NHS because of the limited transparency around financial support transactions