AFTER two false alarms, this time he is coming. We shouldn’t underestimate what an important political moment this is.

Donald Trump has been a disaster for the US people. He has slashed social security and Medicare, ramped up the military budget, cut taxes for the rich, hounded immigrants and re-energised the politics of white supremacy. 

He is threatening abortion rights, tearing up environmental regulation and a whole spectrum of anti-discrimination policies. He is dragging the country backwards.

But Trump has had a terrible international impact too. He has pulled out of the Paris climate change agreement, the only one going. 

He has escalated militarily in the Middle East and Afghanistan, ramped up Nato’s presence in eastern Europe, scrapped the Iran nuclear deal, provocatively declared Jerusalem the capital of Israel and generally brought a crazed, confrontational approach to foreign policy that raises eyebrows even among neocons. 

You know things are bad when a defence secretary widely known as “Mad Dog” Mattis is playing a restraining role in the White House. 

Two things are particularly worrying about Trump's foreign policy. One, it appears to be driven largely by domestic concerns to keep his hard right evangelical Christian constituency on board. 

Second, in Mike Pompeo and John Bolton, Trump has now managed to pull together a foreign policy team that is as extreme as he is. 

All this at a time when the US is facing challenges to its global dominance. With Trump at the helm the risk of big power war is greater than at any time for decades. 

More generally, the presence of such an open racist and xenophobe in the White House has helped legitimate far-right ideas and movements around the world. Trump is a hero to the growing number of Islamophobic and fascist leaders and movements in Europe and beyond. 

It is a badge of pride that Trump has pulled out of two previous visits to Britain. He has admitted this was because he feared being confronted by protesters. 

Now that he is coming we need to deliver the biggest possible turnout. Large numbers on the streets of London will send a signal around the world that millions regard him and his policies with utter contempt and that it is possible to mobilise on a mass scale against him. If we stop Trump coming to London, that will be a victory in itself. 

But there are other domestic reasons why the protests matter. Above all they give us a chance to turn up the heat on Theresa May’s government at a time when it is desperately weak and when the left feels too quiet.  

May has backed Trump in most of his misadventures. She joined in the recent, pointless gesture-bombing of Syria and is aiding and abetting the US-backed Saudi war in Yemen. She is supporting his call for increased military spending in Nato. 

Perhaps most shockingly she has followed him in giving maximum support to serial aggressor Benjamin Netanyahu at a time when the Israel Defence Forces have been slaughtering peaceful protesters in Gaza. 

At home, her government’s attitude to immigrants may not be promoted with Trumpian flourish, but it shares many essentials. 

May and Trump have similar hellish visions of a low-wage, low-tax, privatised future too. On both counts May is deeply unpopular. 

The anti-Trump demo is an opportunity for everyone who opposes austerity and racist immigration policies to take a stand. 

Finally, a big anti-Trump turnout will be a great response to those trying to organise an anti-Muslim far-right in Britain. It is our chance to express solidarity with the Muslim communities in Britain and show that the majority reject the Islamophobic politics of hate.  

Preparations for the protests are going well. The two biggest groups that organised against Trump last time he threatened to come are now collaborating as Together Against Trump.

This means there are a huge range of trade unions, campaigns, community groups, politicians and celebrities behind the call for a national demonstration assembling at the BBC at 2pm on Friday July 13 and other protests during his time in Britain.

New groups keep getting in touch wanting to organise feeder marches and blocs including a Stop Trump party, with some of the world’s biggest DJs, that is feeding into the march on Friday July 13.

Given the level of contempt for Trump and everything he stands for in Britain, we should be looking at very big and lively protests. That depends on what each of us does from now to get the word out. 

We have just over a month. Let’s give Trump a reception he won’t forget and the world can’t ignore.

Chris Nineham is vice-chair of the Stop the War Coalition.