Theresa May is going to meet Donald Trump next month, soon after he is inaugurated as the 45th President of the United States. It will be an occasion of great symbolism but possibly little substance. Mr Trump remains wilfully unpredictable, and could say anything. Ms May remains stubbornly formal, and could say almost nothing. And yet on the question of whether they can form a working partnership rests a great deal of our geopolitical future.

This is, of course, more true for Britain than it is for the US. We British know that we do not matter much to most American administrations most of the time, yet we console ourselves, not so much with the fiction of the special relationship, because we are too sophisticated for that, but with the times when America has needed us and the bond has been strong.

Mr Trump at least knows who we are. He owns golf courses in Scotland, where his mother was born. In this he is rather different from Barack Obama, born in Hawaii, who often seemed to look at the world out of what we think of as America’s rear window, over the Pacific. Mr Trump seems more instinctively familiar with British culture. He took a political interest in our Brexit referendum, and used it to suggest that his insurgency was part of a global Anglophone movement.

Unfortunately for Ms May, this means that his connections with British politics are with Ukip rather than with the Conservatives. This gives Nigel Farage plenty of scope for mischief. He will attend the inauguration in two weeks’ time, but at least Ms May’s visit means that it will then be harder for Mr Farage to present himself as Britain’s unofficial ambassador to the Court of the Golden Elevator.

The most important subject for Ms May in her talks with Mr Trump is trade. She will find it so much easier to present Brexit as a success if a US-UK free trade agreement is in prospect. The trade deal between the US and the European Union, the Transatlantic Trade and Investment Partnership, which had been three years in the making, appears now to be dead. It was defeated by public sentiment in Europe that its benefits would have been tilted too much in favour of business owners rather than workers and consumers, and Mr Trump’s protectionist rhetoric would seem to be its last rites.

If the UK could steal a march on the rest of Europe by jumping to the front of the queue of which Mr Obama spoke during the referendum campaign, by negotiating our own bilateral deal with the US, it would be a political, diplomatic and economic triumph for Ms May.

And it is possible to imagine how such a deal might fit into Mr Trump’s world view. It would allow him to show that he is no isolationist, while still protecting American workers in the old manufacturing Midwest from low-wage foreign competition. He likes to present himself as an international business person who is good at striking deals: if this were a deal that he could sell as being in the interest of Michigan workers it would be good for him to have it.

Of course, there are many other important subjects that Ms May will raise with the new President, as Andrew Grice writes today. She needs to encourage him to stand by Nato and to distinguish between being friendly to Vladimir Putin and being soft on him. She will try to persuade him to abide by the Paris Agreement on climate change, and to be even-handed on the Israel-Palestine question.