It was hard to imagine a more unlikely place for horror to unfold than a community centre holding a Taylor Swift-themed dance class in the sleepy seaside town of Southport. So when three little girls were murdered and eight other children and two adults viciously stabbed by a 17-year-old boy, it seemed incomprehensible. But before the shock could wear off, misinformation and lies about who had unleashed this misery began to spread. The result was days of racist riots and violence.

Josh Halliday, the Guardian’s North of England editor, covered the attacks, the riots and now the court case of Axel Rudakubana as he was sentenced to 52 years in prison. On Monday, as the jury was expected to be sworn in, the now 18-year-old Rudakubana shocked everyone by pleading guilty to all the charges he was faced with. And this week the judge gave him a life sentence.

But while the case was cut short, one thing was very clear – the repeated and worrying failures to stop this dangerous and troubled young man from hurting others. Josh describes Rudakubana’s history of violence, how he took knives to school and on public transport, and even called Childline to tell them he wanted to kill someone; how he was referred to the government’s anti-radicalisation programme, Prevent, three times – and how his own parents repeatedly called the police because of their worries over his frightening behaviour. Now Helen Pidd hears how the government has announced they are launching a public inquiry, a review of Prevent, and are even thinking of changing the definition of terrorism.