MI5 boss Ken McCallum has said he is "profoundly sorry" and "deeply regrets" the security service's failure to prevent the Manchester Arena Bombing atrocity.
In an unprecedented move, the security service has issued an apology for its failure to stop the attack, which saw Salman Abedi detonate his homemade device at the end of an Ariana Grande concert in May 2017.
The explosion killed 22 people and injured hundreds more and remains the deadliest terror attack in Britain since 7/7.
