The Department explained that it is working closely with the Public Sector Fraud Authority to identify the best methodologies, but cautioned that measuring potential fraud loss is “really difficult”.37 The Department also explained that it is seeking to learn from the NHS Counter Fraud Authority, which has experience publishing a high-level fraud loss estimate broken down by thematic risk areas.38 It told us that its impression from looking at the NHS is that it this is “incredibly complex and challenging” which, it explained, is why it does not believe it will be able to quickly produce a similar estimate for the whole of defence, but will instead over the next year focus on the areas of highest risk.39