In 2003 the Cabinet Office published its study into improving the role and impact of inspection and external review of public services.
It concluded that inspection and external review have a key role to play in
However, the effort put into inspection and external review (both by inspectorates and those inspected) must be focused in a way that will have the maximum impact on service improvement and deliver real value for money
The report can be downloaded here
Inspecting for improvement: Developing a customer focused approach [PDF 235KB, 61 pages]