families of the dead victims and an increasing number of 7/7 survivors claim there are inconsistencies and basic mistakes in the official accounts that need explanation.
And they are demanding a full public inquiry to answer key questions about what the Intelligence Services and the police did and did not know before the bombings.
Meanwhile, the Government's determined refusal to meet their demands is having a very dangerous side-effect - fuelling myriad conspiracy theories about 7/7. Books, blogs and several video documentaries point to oddities in the official accounts.
The survivors are so intent on an independent inquiry that they are now taking legal action in the High Court to try to force the Home Secretary Alan Johnson to authorise it.
Central to the puzzle is which train the four Muslims caught from Luton to London on the morning of the bomb blasts - bearing in mind that the three separate Tube explosions at Edgware Road, Aldgate and King's Cross occurred together at exactly 8.50am, followed by the red bus an hour later near Tavistock Square.
The official reports said the bombers got on the 7.40am train from Luton which would have arrived at King's Cross in good time for them to board the Tube trains.
However, the 7.40am train never ran that morning. It was cancelled.