The issue of Private Finance Initiative (PFI) schemes, as they affect published official statistics, has been the subject of a number of ONS published articles. Recent articles can be found at the following locations:
(i) Nov 2006 Economic Trends article, "Including finance lease liabilities in public sector net debt: PFI and other", by Adrian Chesson and Fenella Maitland-Smith.
http://www.statistics.gov.uk/articles/economic_trends/ET636Chesson&MaitlandSmith.pdf
(ii) May 2008, Economic & Labour Market Review article, "Private finance initiative and public debt", by Martin Kellaway:
http://www.statistics.gov.uk/ELMR/05_08/downloads/ELMR_May08_Kellaway.pdf
(iii) July 2009, Economic & Labour Market Review article, "Government financial liabilities beyond public sector net debt":
http://www.statistics.gov.uk/statbase/Product.asp7vlnks14692