In the days after the London bombings in July 2005, the UK's domestic intelligence agency MI5 claimed the bombers were "not on our radar".
However, Tuesday's Intelligence and Security Committee report shows that 7/7 leader Mohammad Sidique Khan was all over their screens on dozens of occasions over a four year period leading up to the attacks, but MI5 and the police failed to connect up the dots.
Khan, was photographed by a surveillance team at a terrorist training camp in January 2001.
He and another of the bombers, Shehzad Tanweer, were filmed and recorded with Operation Crevice fertiliser bomb plotters in 2004 talking about the success of the Madrid bombings.
Police National Computer checks were made 21 times in a year on Khan's car in connection with Operation Crevice.
There was a catalogue of missed chances.
As late as June 2005, just two weeks before the 7/7 bombings, MI5 launched an operation specifically to try to track down a man called Ibrahim - Khan's alias.
Yet the Intelligence and Security Committee report says that 7/7 could not have been prevented.
On tonight's Newsnight, Jeremy Paxman will be asking a senior member of the committee just how they came to this conclusion, and Richard Watson will be reporting .
Newsnight, 10.30pm on BBC Two.