This begs the question of how Mossad was warned of the activities of a highly secretive mission by an "al Qaeda sleeper cell" consisting of three or four people:

"The way these folks work, they can go the logistics planning, to get the equipment they need and do the surveillance. Al Qaeda-trained people do a tremendous amount of surveillance to find the right targets, the right time of day or whatever. But then, you can put all those plans and equipment on the shelf, and then with one phone call, in as little as 24 hours, execute those plans." CBS News

Also, Mossad knew of the attacks at 08:45, and this may explain the revised bombing times:

The three bombs on London underground trains on Thursday exploded almost simultaneously, police have said. Scotland Yard said the attacks took place within 50 seconds of each other. It was previously thought they had taken place over a longer time period. BBC News

The original timeline shows the last subway bombing occurred at 09:17:

9.17AM: Five people are killed in an explosion at Edgware Road Underground station. Police said a blast ripped through a carriage, a wall and into two other trains. manchesteronline

The new timings gave Mossad only 6 minutes to warn of the attacks, but the original timings gave them 32 minutes to issue a warning before the last explosion.

No warnings were issued.

Also remember it was thought that the explosions were caused by power surges up until 10:00:

10.00AM: The National Grid, which supplies power to the Underground, confirms there have been no problems with its system. manchesteronline

How long does it take Mossad to pick up a phone?>

See also:The 7/7 London Bombings: Who Benefits?