1. Can the intelligence services be accused of failure?
Ministers and police insist not; the answer is unclear as yet. If previously unknown British nationals are behind the atrocity, it will be hard to pin the blame on MI5. But if a vital piece of intelligence was overlooked, there will be recriminations throughout the security services.
2. So who was behind the attacks?
Very little is known. Although Scotland Yard and the Government said they bore all the hallmarks of al-Qa'ida, none of the suspected al-Qa'ida sympathisers monitored by the security services appears to have been involved. That leaves the grim possibility that the perpetrators were a loosely-organised group of British citizens living apparently conventional lives. Have they fled the country or are they lying low?
3. What was the significance of the timing?
Impossible to say for certain, although the obvious conclusion is that it was arranged to coincide with the meeting of the world's leaders at the G8 Summit in Gleneagles. But why did the perpetrators not attack during the general election, as many politicians and security experts had feared? Was London's success in winning the Olympics the previous day a factor? Unlikely, as it would have taken more than 24 hours to plan the attacks.
4. Why were these specific targets chosen?
A question puzzling investigators. Aldgate could have been chosen because of its proximity to the City of London. King's Cross is one of the city's busiest transport hubs, while Edgware Road is close to both Marylebone and Paddington stations. There is no obvious reason to select Tavistock Square for blowing up a double-decker bus.
5. What could have been the reasoning behind the bus attack?
It could have been a deliberate recreation of explosions on buses in Israel. The bomb could have exploded accidentally as it was being carried to Oxford Street, the capital's busiest shopping artery.
6. Were they suicide bombings?
The theory has not been ruled out, but police say there is no evidence to support it. The three blasts on Tube trains are believed to have come from packages left on the floor, suggesting that they were left behind, rather than strapped to suicide bombers.
7. Could they strike again?
Unknowable, although police have warned that is a grim possibility. The Madrid bombers had planned further atrocities, but were tracked down in time.Reuse content