The NAO has played an important role in looking at the PFI/PPP experience in the UK. Their report on the Fazakerley PFI prison contract, for example, revealed the need to share the gains from refinancing PFI/PPP contracts to protect value for money for the taxpayer. Over the years, the NAO has audited many transport PPP projects drawing lessons that are relevant to PPP projects. Examples are the first four Design-Build-Finance-Operate highway projects in the UK, the Channel Tunnel rail link and the London Underground PPP contracts.

http://www.nao.org.uk/publications.aspx