Apparently when President Trump signed his executive order to ban refugee, among others, from seven predominantly Muslim countries from entering the US Mrs May was on an aeroplane, tired and without time to think. So her first public pronouncement was a metaphorical shrug of the shoulders: The US policy on refugees is a matter for the US and nothing to do with us.
As a former Home Secretary she should have known, and if she didn't one of her multitude of advisers on the aeroplane should have told her, that the 1951 Refugee Convention is a United Nations International Convention, subscribed to at the time by 145 countries, including the US and UK, and in which both British and American lawyers were involved in the drafting. It is part of international law, and we believe in the Rule of Law. Deviations from international law are not "nothing to do with us" but something on which the UK should strive to uphold, even if the the deviations are by the highest and the mightiest.
Of course in view of the international and national outrage provoked by President Trumps improvident action Mrs May has been quick to change her tune (though Boris Johnson's reaction that it's all right really because his special relationship has allowed an exemption for Britons with dual nationality is pathetic). But Mrs May's initial response makes it clear that she is seriously lacking in moral compass. Now that the most powerful country in the world is in the hands of a maverick, leaders with strong moral compasses are desperately needed.
It is possible that the Trump regime may not be as disastrous for liberal values as his campaign rhetoric predicts. If so, as the last ten days or so indicate, that will not be through any lack of determination by Mr Trump but through the robustness of the American Constitution. This entrenches the principle of "Separation of Powers." The Executive (the President and administration), the Legislature (Houses of Congress) and the Judiciary are independent and act as checks and balances on each other.
With a liberal president in office this can be a cause for frustration, and with Congress in the hands of the Republicans many of President Obama's progressive reforms were either seriously diluted or blocked altogether. However, although he Republicans still have a majority in both Houses of Congress, many of the individual Republicans are far from Trump supporters, and may well provide the necessary checks, as indeed a decision of a Federal Judge that the travel bans are illegal already has. The rights of individual states are also well entrenched by the Constitution
For years we British have boasted on the advantages that the flexibility of our "unwritten" constitution, with any necessary checks and balances provided by conventions, gentlemen's agreements and our innate predilection for "fair play" Clearly these three can no longer be relied on, so we desperately need a written constitution, not least to entrench the rights of the devolved administrations and local government.
Alas fundamental issues such as this will be placed on the back-burner whilst the political establishment veers with the wind whilst haggling over an issue most of them believe shouldn't happen.