If there had been cooperation and communication between Britain's security and law enforcement agencies, the guy never should have been allowed to board that plane. MI5 was aware of him, as well as the police. He'd had several previous arrests. As usual, the incompetency of people who are relied on to keep us safe, once again put innocent lives in danger. It happens way too often.
Re: incompetency of people
To label this incompetency is assuming that those running these agencies are people of good will.
I am now beyond assuming “incompetency”. Moral corruption is the more likely reason.