Like jackals circling their prey, the British far-right could barely wait to take advantage of yesterday’s Westminster terror attack. This was a chance to say “we told you so” after Donald Trump’s election and criticism of his approach to security; they wasted no time in pressing their point.

Just a few days ago the former BNP member Jack Buckby, who ran as a candidate in Jo Cox’s seat after her murder, wrote: “Exit polls suggest a left wing coalition in Netherlands. Horrible thing to think, but only terror attacks can save Netherlands now. Wake up.”

Buckby stated, out loud and in public, what the far right had been thinking since Trump’s inauguration in January: an Isis-inspired terror attack is just what they need to shore up their popularity. The former leader of the EDL, Tommy Robinson, was so desperate to drum up publicity that he rushed to reporters in Westminster within minutes of the atrocity. Not to be outdone, Britain First called for a demonstration on 1 April (a date, in my view, quite suited to their band of thugs).

The far-right is emboldened because it knows it has an ally in the White House to help its narrative. In January, John Cardillo, a commentator on Fox and NRA News tweeted: “When it’s revealed that the #QuebecShooting terrorists are Muslims, #Trump will have a tremendous spike in political capital.”

Westminster falls silent in memory of terror attack victims

Except the Quebec shooter wasn’t a Muslim. That tweet was nevertheless “liked” by Donald Trump Jr.

For them, this isn’t just a war against terrorists – it is a war against everyone they think are allies of Isis: Muslims, immigrants, liberals and the left.

They hate the very idea of cosmopolitan communities. Just hours after London was attacked yesterday, right-wing columnist Katie Hopkins called our capital city “an entire city of monkeys”.

The last terrorist attack on British democracy was the murder of Labour MP Jo Cox by Thomas Mair, a far-right fanatic. Did the right, at that point, call for better surveillance or “vetting” of white nationalists groups? Obviously not.

What about when a London knife-attacker shouted, “Death to Muslims, go back to Syria” in December? There was a remarkable unwillingness to ask public questions about the causes of “white radicalisation” then too.

That isn’t to say Isis-inspired extremism is not a problem; it absolutely is, as yesterday’s appalling events reminded us. We need to examine and tackle all forms of extremism. Isis is not simply a reaction to western foreign policy but its own form of murderous imperialism. And it has its roots in earlier ideological terror groups such as the Taliban and Hizb ut-Tahrir.

But it’s no exaggeration to say that white nationalism, as expressed in the immediate response to the Westminster terror attack yesterday, is merely the ideological mirror-image to Islamist extremism.

Such groups may not be responsible for large scale terror attacks in the Middle East, but nevertheless pose a significant threat in the West. A study in 2015 found white extremists had killed more Americans in the US than jihadists since 9/11. Yesterday, while focus was on London, another white nationalist in NYC admitted to murdering a black man because of his race.

Far-right extremists are now a majority of referrals to the anti-terrorism programme in some parts of UK.

Terror attacks such as that in Westminster illustrate the growing symbiotic relationship between the far-right and Islamist extremism. Both sides need each other to spread panic and terror; to create tension and paranoia; to further the “clash of civilisations” they are itching for. The aim of white nationalism and Isis-inspired extremism is the same: to radicalise their own side, to undermine and destroy moderates and to create conflict.

Londoners have survived worse than this. The city epitomises the spirit of the “Keep Calm and Carry On” motto popularised during World War Two. Earlier generations weathered the German bombing of the Blitz, and Londoners survived the terrorist attacks of 7 July 2005.