To stop the next Manchester attack, MI5 must find the next young man growing up in a petri dish of hate

Flowers and tributes for the victims of the attack on Manchester Arena, where 22 people died. Photograph: Phil Noble/Reuters

Ramadan Abedi had done his best as a father, he insisted.

He tried to intervene with his sons when he “found their thinking is wrong”, but it hadn’t worked. He could almost have been shrugging off a set of flunked GCSEs, or some minor teenage brush with the law. But in fact that whiny, self-justifying message to his sister was written after his son Salman detonated a shrapnel-packed bomb in the crowd leaving an Ariana Grande concert in Manchester, killing 22 people.