It takes months to become a real bad guy, to turn against a whole race of people, to boast about your lack of compassion, to whip even your most craven allies into grovelling silence as you besmirch the good name of your country. But it took only a few seconds for Justin Trudeau to shame Donald Trump at the weekend. All he said was “Welcome to Canada”, and his own freezing, cantankerous, glorious country became the Land of the Free.

It was a lesson, if she had the wit to grasp it, for our own little poodlet – whose frightened complicity when asked, repeatedly, to respond to Trump’s meanness of heart shamed even her own cabinet of buffoons. Is this where Brexit has taken us?

So let’s just appropriate the tweet she should have sent after her meeting with the American President with whom she wants a “special relationship”: “To those fleeing persecution, terror and war, Britons will welcome you, regardless of your faith.” It even has a touch of British guts about it – the kind a few good souls demonstrated when they brought the Jewish children of the Kindertransport to the UK and saved them from Hitler’s extermination camps.

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But that was too much for Theresa May. The message wasn’t sent out to the masses yearning to breathe free by a proud Britain, but by a united and self-confident Canada. It will be Canada that welcomes “those fleeing persecution, terror and war”, not a Britain whose pitiful Prime Minister goes begging for save-our-face trade deals with a man who cares nothing (like her) if British Muslims also want to visit America.

Trudeau’s re-publishing of a picture, which showed him greeting a Syrian child at Toronto airport just over a year ago – the first of 39,000 refugees to come to Canada – was worth a thousand words. Instead of hiding behind May’s mean-spirited “render unto Caesar” approach, Trudeau merely let it be known that he “looked forward to discussing the success of Canada’s immigration and refugee policy” with Trump.

No, Trudeau didn’t condemn Trump. It wasn’t necessary. Not just because 75 per cent of Canada’s exports go to the US. Not because more than 20 per cent of Canada’s population are themselves foreign-born immigrants. Not because Trudeau’s own immigration minister is a dual national who arrived in Canada as a Somali refugee – from one of the seven countries whose refugees are “temporarily” blacklisted by Trump. Nor did Trudeau need to rub salt in the face of Stephen Harper, the Conservative right-wing anti-immigrant, anti-Muslim prime minister he decisively beat in Canada’s October 2015 national elections. Harper had wanted to set up a police hotline for citizens to report “barbaric cultural practices”.

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Of course, we mustn’t get romantic. Trudeau’s a sleek guy with his father’s knack of both annoying and energising his nation. Pierre Trudeau saw off the Quebec sovereignty movement in a manner that May showed no spirit for when confronted by Ukip and her own home-grown separatists. But Pierre could be a vain, self-regarding man, and young Justin – with his cool dismissal of big money and penchant for self-advertisement – is not without his flaws. His wife Sophie is a lot smarter than Melania; she doesn’t have to crib Michelle Obama’s speeches when she speaks in public. But did the Canadian couple really have to pose for Vanity Fair?

And Canada’s immigrants don’t all live peachy lives. There’s a ghetto mentality about parts of Toronto. West of the capital, you can colour Mississauga a Muslim green. There are tribal gangs in big cities. Diversity does not always mean strength, as Trudeau tweeted. But for that matter, you colour Dearborn, Michigan, green. Some Canadian immigrants do better than others. Afghans have a hard time assimilating. But Canada wants its immigrants to keep their own cultures alive in their new home. The government encourages foreign language radio stations and newspapers. Canadian business has learned to use its top Pakistani, Chinese or Arabic staff as senior management for Canadian companies, speaking their parents’ language in their countries of origin.

And so Trudeau’s government has even ensured that its dual national citizens will not be harassed by US Homeland Security when they visit America. Did May do that? Forget it. Those are not the kind of British citizens she cares about.