Police sources confirmed to The Independent that footage taken from a number of cameras was obscured at 5pm - the time that detectives believe the bomb was left at a bus stop just yards from where it exploded half- an-hour later.
Despite receiving a call from a person purporting to be a member of the far-right group Combat 18 claiming responsibility for the bombing, police so far have no clear lead. They were hoping that the film footage would provide that.
Officially, police refused to confirm the setback. Last night a spokesman for the Metropolitan Police's anti-terrorist unit said: "Officers are still analysing footage. It would be inappropriate to comment at this time."
Last night, the 23-month-old boy who had surgery to remove a four-inch nail from the bomb embedded in his head left Great Ormond Street hospital in high spirits. There was still concern for the eyesight of two of the bomb victims being treated at King's College Hospital.Reuse content