British teenager Axel Rudakubana, 18, pleaded guilty to the murders on Monday, following the knife attack at a Taylor Swift-themed dance event last year – a crime that led to days of violent riots.

“The blunt truth here is that this case is a sign the UK now faces a new threat. Terrorism has changed,” Starmer told a press conference.

“In the past a predominant threat was highly organised groups with clear political intent, groups like al Qaeda.

“That threat, of course, remains, but now alongside that we also see acts of extreme violence perpetrated by loners, misfits, young men in their bedroom accessing all manner of material online, desperate for notoriety, sometimes inspired by traditional terrorist groups, but fixated on that extreme violence, seemingly for its own sake.”

The government has announced a public inquiry into the murders, promising to examine the failures of state institutions that were warned about Rudakubana, but which failed to prevent the attack.

Starmer said the country’s terrorism laws could be changed if needed.