The Inquiry is not the first investigation into the question of whether the Security Service and/or Counter Terrorism Policing could have prevented the Attack. Both the Security Service and Counter Terrorism Policing carried out their own Post‑Attack Reviews. These were conducted in 2017.
David Anderson QC (now Lord Anderson KC) conducted an independent assessment of the Post‑Attack Reviews and produced his report in December 2017.In his summary, Lord Anderson stated:
Detailed consideration was given to the way in which MI5 [the Security Service] in early 2017 handled the intelligence, whose true significance was not appreciated at that time. On this, the review team concluded in summary that:
- the decision not to re-open an investigation was ‘finely balanced’ and ‘understandable’ in the circumstances;
- there is a degree of inherent uncertainty in speculating as to what might or might not have been discovered if an investigation had been opened on the basis of the new intelligence; but that
- on the clear balance of professional opinion a successful pre-emption of the gathering plot would have been unlikely.
Lord Anderson concluded:
“[I]t is conceivable that the Manchester attack … might have been averted had the cards fallen differently.”
The Intelligence and Security Committee of Parliament also investigated what had happened. It published a report on 22nd November 2018 entitled The 2017 Attacks: What Needs to Change?. The Committee relied, as it had to, on the Post‑Attack Reviews, along with the evidence of senior members of the Security Service and Counter Terrorism Policing. These people were not the original decision‑makers on the ground.
The conclusions of the Intelligence and Security Committee of Parliament in relation to SA included:
“[SA] should have been subject to travel monitoring and/or travel restrictions. ***, MI5 [the Security Service] should have put alternative measures in place to alert them to [SA]’s movements.
The Committee notes MI5’s assessment that had [SA] been placed under travel restrictions, there still may not have been sufficient time to identify or act on his attack planning. It would, nevertheless, have provided more of an opportunity.”