-> 'I really wanna shoot up the school'; How two boys planned Columbine inspired attack in North Yorkshire In the trial opening, Paul Greaney QC, prosecuting, told Leeds Crown Court: "Once you have heard the evidence, you may conclude that the police in North Yorkshire responded inadequately to the threat these two defendants presented, although a month later a specialist anti-terrorism team who became responsible for the investigation responded more appropriately, and robustly.
"The reason why we recognise that you may consider the initial police response inadequate is because, even after the disclosures (of one of the boys) in late September, (the boys) remained free."
The jury was told how the police became involved with the older boy after he was excluded from school for social media posts mocking a teacher.
-> 'I love murderers, we need to aid natural selection' - North Yorkshire school massacre plot teen wrote in diaryFour months later, both boys were spoken to separately by police at home after one told a teacher about their plans for a school attack.
He told officers of their plan to kill students at school due to bullying, prosecutors said.
Mr Greaney said the teenager told officers they "planned to go into school with a firearm in order to get rid of those who had wronged them" but the older boy denied everything.
The court heard that the older teenager was researching the Columbine massacre within minutes of the officers leaving.
The older boy was later arrested by North Yorkshire Police for alleged offences relating to his girlfriend and her family.
In a statement, assistant chief constable Phil Cain said: We fully accept that standards of investigation and our initial responses, to some of the incidents, did not meet those standards that are expected of us and what we strive to deliver.
-> Police reveal bomb materials and messages of teenage boys in deeply unsettling North Yorkshire school massacre planThese were unusual circumstances, and once the seriousness of the allegations were realised, we turned to the North East Counter Terrorism officers for their specialist assistance and support.
A senior officer has since reviewed the issues and addressed these with a number of officers and staff.
We will continue to asses our policies and procedures to ensure our officers provide the best possible service to the public.
I offer my reassurance to the communities of North Yorkshire that the safety of the public remains paramount.
Speaking outside Leeds Crown Court, North Yorkshire Police's head of safeguarding Allan Harder was asked repeatedly whether the force made mistakes but did not answer.
He said: "In terms of any investigation, there's always lessons to be learned - positive lessons and lessons to be taken forward to best practice. We'll review that and we'll be taking any learning from that."