But a summary of the findings revealed that the attack on Manchester Arena that killed 22 people might have been prevented if different decisions had been made by MI5. Anderson said: “On two separate occasions in the months prior to the attack, intelligence was received by MI5 whose significance was not fully appreciated at the time. Dan Hett, whose brother Martyn died in the Manchester attack, said: “I can’t imagine the kind of complexity that these services deal with, and the level of decision that they need to make constantly ... MI5, in the weeks before Butt and the two others struck at London Bridge, was still trying to gauge what danger he posed. Masood was the third person known to MI5 to attack in 2017 and was a former suspect, who used YouTube to help prepare his attack.

Source: The Guardian December 05, 2017 13:50 UTC