One common explanation - favoured by the coalition - is that Labour took a much too rosyview of the underlying state of the public finances in the years leading up to the crunch.
According to Martin Neil Baily, a senior fellow at the Peterson Institute for International Economics in Washington, the "striking thing" about last year's report was that it painted a rosyview of the trade imbalance by focusing on the capital account surplus, rather than its inverse, the current account deficit.
The faulty system (which the company says has now been fixed) persuaded Oxford to take too rosy a view of its financial position, overestimating its revenues and membership and underestimating how much it owed to doctors and hospitals.