MI5, Britain's security service, is steeling itself for criticism over London's July 7 bombings in a long-awaited report from the parliamentary intelligence and security committee, writes Richard Norton-Taylor.
Leaks are beginning to emerge - the latest was to the BBC today. Under a headline on its website proclaiming "Security 'not at fault on July 7'", the BBC said MI5 could not be blamed for the attacks. But it is not as simple as that.
MI5 has told the committee, which meets in private, that there was an intelligence gap - which is obvious - but not an intelligence failure. MI5 argued that, given the resources at its disposal, it could not have watched Mohammed Sidique Khan, leader of the July 7 suicide bombers. He had come to the notice of MI5 but was suspected of fraud, not considered a serious a threat.
A key point is that neither MI5 nor any other part of the security and intelligence world was prepared to believe home-grown Islamist extremists, or disaffected young Muslims, would ever carry out suicide bombings in Britain.
This is not to say a more imaginative approach, and better intelligence, would necessarily have prevented the July 7 attacks. There is no such thing, certainly not in a democracy, as complete security and blanket intelligence cover.
But in its report due to be published next month, the intelligence and security committee is certain to point to terrorist threat assessments that those responsible for our security got completely wrong. A month before the July 7 bombings, they lowered the terrorist threat level. Moreover, they were planning to lower it again on the morning of the July 21 failed suicide attacks in London.
"This underlines the need for an independent inquiry to show us where things went wrong," Patrick Mercer MP, the Conservative party's homeland security spokesman, told me today.
He is unlikely to get it. We will have to rely on the committee's report - which is read by Tony Blair and his security and intelligence advisers, who will decide what passages should be seen by the public.
