This book explains from a public law perspective the constitutional purpose and significance of audit. It also describes and analyses the constitutional significance of the changes to the role of audit that are currently taking place as a result of `New public management'. The effects of developments, such as the creation of agencies, contracting-out, and more recently, resource accounting and budgeting, and devolution, on the constitutional role of audit are considered. The focus of the book is central government audit in Britain. The constitutional role of audit at local level and at European Union level is also considered. Any shortcomings are identified and suggestions for change are explored.