Hazel Simmons, Labour leader of Luton Borough Council, said: “When we heard the revelation that he planned to cause further harm after the terrible murders [there] was shock, upset, concern.”

She said she had received emails from some concerned parents of St Joseph’s pupils.

“Obviously I can’t underestimate how the parents and the school must be feeling at the moment and I can assure them we will do all we can to work with them around the security at the school and any other help that they need at this time,” she said.

Ms Simmons added that she did not know whether the family were known by the council to have problems.

Schools across Luton had already been asked to review security after a fatal knife attack at a school in Sheffield, but the council has asked them to conduct a further review in the wake of Prosper’s admissions.

Prosper will be sentenced over the course of two days next week, during which many more details will be made public.

What is already clear is that his actions have torn a family apart.

Bedfordshire Police’s Det Ch Insp Sam Khanna said: “This was a truly tragic and shocking case in which three innocent members of the same family have been brutally killed by their son and brother.”