Something went seriously wrong when the Libyan terror attack suspect detained over the horrifying killings of three people in a Reading park was known to MI5.
We commend the bravery of the police officer who rugby tackled Khairi Saadallah, 25, but an urgent inquiry is needed to reduce the likelihood of any mistakes in the future.
Grieving families of the three dead, and the injured, deserve detailed explanations – and the wider public requires reassurance the security services are doing their jobs properly.
MI5 must produce answers immediately instead of trying to avoid accountability. Nobody pretends what they do is easy and credit is due for those plots they have foiled.
But what happened in Reading is another grim reminder that terrorism remains a mortal danger.
