The condemnation by the UK Government of Donald Trump’s crackdown on immigration from seven Muslim-majority countries was, if belated, welcome nonetheless. The US President’s latest executive order is the most worrying of those he has made thus far, as discriminatory as it is facile. There is little evidence that terrorists have been entering America as refugees from the countries on Mr Trump’s list: as with so much of the President’s first week in office, the symbolism matters to the man in the White House as much as practical effectiveness. That’s not to say his latest move was without consequences though – far from it, as several hundred individuals already travelling to the US soon found out.

Theresa May appears to have been caught on the hop by the presidential decree, initially declining to say on Saturday whether she disapproved of a policy which other leaders were quick to censure. For all those buoyed by the apparent success of the Prime Minister’s visit to Washington on Friday, this should prove something of a wake-up call. First, it must be plain that Ms May was unaware that the President’s pen was metaphorically hovering over such a monstrous order as the pair merrily discussed the “special relationship”. Second, her failure to object immediately to the travel ban shows just how desperate the British Government is to avoid upsetting the American administration. That suggests a weakness that is hardly likely to prove helpful in upcoming discussions over a US-UK trade deal.

Indeed, the Prime Minister spent much of last week reassuring both the British public and other world leaders that she was not about to become a poodle to Trump’s rottweiler. Yet when faced with an unexpected test of her mettle, she declined to bark let alone bite. Instead, it was left to her spokesperson many hours later to confirm that Downing Street does “not agree with this kind of approach”. The Prime Minister may be renowned for thinking long and hard before committing herself to policy positions – but that is not always possible, and it should have been abundantly clear that refusing to offer a view on MrTrump’s most recent executive order would not wash.

Boris Johnson, who as Foreign Secretary has been more liable to show up the Prime Minister by gaffes than good sense, rather highlighted his boss’s mealy mouth by tweeting that it was “divisive and wrong to stigmatise because of nationality”. Theresa May’s counterparts in other Western European countries were even more forthright, underscoring their anxiety that President Trump is not only bombastic and protectionist but may be on the verge of dismantling the liberal, democratic consensus which has been the cornerstone of Europe’s relationship with the US for decades.

Angela Merkel’s spokesman indicated that the Chancellor “regretted” the President’s decision and had expressed her unease during a phone conversation with Mr Trump on Saturday. He went on: “She is convinced that the necessary and determined fight against terrorism does not justify placing people of a certain origin or a certain religion under a generalised suspicion.” The Prime Minister is no clone of Ms Merkel, nor does she need to be. But if she wants to ensure that Britain retains its influence in the post-Brexit world, it is vital that she stands up for the sense of fair play which this country is supposedly famous for.

Of course, the truth is that if last summer’s referendum to leave the European Union came as a shock, then it was as nothing compared to the thunderbolt which was Donald Trump’s election win in November. And it has thrown Britain’s prospects for life outside the EU into entirely unexpected territory. After all, despite Friday’s hand-holding and positive mood music, it remains to be seen whether America under a protectionist President will really be the marvellous trading partner envisaged by Downing Street.