BBC security correspondent Frank Gardner looks at the loss of top-secret documents by a civil servant and considers its ramifications.
Who lost the documents?
A senior intelligence official who was seconded to the Cabinet Office and had clearance at the highest level to handle very sensitive information not just from the UK but allied sources, including the US.
What has been the reaction?
Britain essentially has egg on its face.
This is very embarrassing because Britain has had to apologise to its allies and everyone who contributed to this intelligence.
The reaction in Whitehall was one of absolute horror, recriminations and soul searching.
What did the documents say?
There were two documents.
One was about the state of Iraq's security forces, which was commissioned by the Ministry of Defence.
The other one, which was much more sensitive, looked at al-Qaeda's vulnerabilities.
This document was jointly commissioned by the Foreign Office and Home Office.
If it fell into the wrong hands, it would have given a clear picture of the strategic overview that the UK government and allied countries have about al-Qaeda, its weaknesses and where these failings could be exploited.
It could have been damaging if it fell in the wrong hands.
This did not involve raw intelligence that said: "Agent X can reveal that...". There were no lists of informants, or anything else of that nature.
The lost documents were strategic. Raw information is collated by intelligence agencies, who then process it and send it to the Joint Intelligence Committee, who put together assessments in the form of strategic documents.
These were polished documents that were intended for certain ministers and senior officials only.
Have media reports been censored?
There has been enormous pressure to gag the BBC and the rest of the media over this, without success.
We have not broken the Official Secrets Act, we have not revealed specifics of what is contained in the documents and we have not undermined national security.
How common is the loss of such documents?
There have been some close shaves - a few. People have lost material that we don't hear about and are only now finding out about.
But this loss involved some of the highest rated security documents to have gone missing.