Shortly before turning the gun on himself, the 22-year-old uploaded a video to YouTube titled Elliot's Retribution, in which he described his motives as wanting to "punish women who had rejected him" as well as sexually active men because he was jealous of them.

In a lengthy online manifesto, he also wrote: "If I can't have girls. I will destroy you."

Two years ago, Alek Minassian, a 27-year-old software engineer, killed 10 people in a van attack in the centre of Toronto, which was also said to have been inspired by an incel mindset.

Following the attack, police found a Facebook post in which Minassian boasted that the "incel revolution" had begun.

He was subsequently arrested and during interview told police he was a virgin who had never had a girlfriend. He allegedly told officers he had used the van in the hope of inspiring more incel attacks around the world.

There have been at least four other mass shootings in the United States and the death toll now stands at almost 50.

Experts who monitor the online activities of incel extremists believe it is only a matter of time before the UK witnesses a violent attack by someone identifying with the ideology.

It is estimated that there could be as many as 2,000 men in the UK who label themselves as incels, but most are highly secretive and post anonymously.

Annie Kelly, a PhD research student at the University of East Anglia, who has carried out extensive research into online misogyny, said it was hard for the authorities to build up a clear picture of what was going on.

"There are numerous forums out there on which men identifying as incels post, but it tends to be a global network so it is hard to get a sense of the UK picture.

"Also, men might be posting in these online forums without really being serious.

"But much of the language is very violent and given what has happened in the US and Canada, it does seem like it was only a matter of time before we saw something here.

"There is nothing in the British culture that sets us apart and makes it less likely to happen here."

The danger posed by violent incels is just one of a new breed of potential threats counter-terror police are having to monitor.

It is estimated that there are as many as 25,000 jihadists living in the UK today, and there has also been a huge rise in the number of far right extremists, with two more groups outlawed by the Government last month.

Counter-terrorism police have also seen an increase in the threat posed by "lasits", Left-wing, anarchist or single-issue terrorism.

As well as incels, this might include extreme animal rights activists or so called eco-terrorists.