Sir Keir said he had known details of the case emerging following the attack, but contempt of court laws forbade him from disclosing them sooner.
He said: “If this trial had collapsed, because I or anyone else had revealed crucial details while the police were investigating, while the case was being built, while we were awaiting a verdict, then the vile individual who committed these crimes would have walked away a free man.”
As well as being referred to Prevent three times between 2019-2021, Rudakubana was excluded from school aged 13 in October 2019, after which he returned to the school in December that year with a hockey stick and assaulted a pupil, breaking their wrist.
Lancashire Child Safeguarding Partnership said Lancashire Constabulary responded to five calls from his home address, between October 2019 and May 2022, relating to concerns about his behaviour.
Rudakubana also called Childline several times as a young teenager, eventually telling the service he was going to take a knife into school because of racial bullying.
The prime minister said he would not let any state institution “deflect from their failure – failure which in this case, frankly, leaps off the page”.
He said it was “clearly wrong” Rudakubana was deemed not to meet the threshold for intervention from the Prevent programme, and the Southport victims’ families had been failed.
“And I acknowledge that here today,” he added.
