Trump's coming to dinner, and Britain will welcome him — sort of

Many of us have issued hasty invitations we later regret to people we don't know that well — but Theresa May topped the scale with her offer of a state visit to Britain when she saw President Donald Trump in the first week of his presidency.

Naively, she hoped it would mark the start of a warm alliance between them, leading to an easy trade deal after Brexit.

Instead, Trump pocketed her offer, went on to praise Boris Johnson as someone who "would be a great prime minister," made London the target of some of his most boorish tweets and never had any intention of opening up U.S. markets to British goods without flooding Britain with low-standard food products in return.

Now that Democrats have taken control of the U.S. House, he can't even offer that — as a more thoughtful U.S. visitor, the House Speaker Nancy Pelosi, reminded us last week.

So how should we in the U.K. react to news that the president is set to turn up for a state visit at the start of June, amid events marking the 75th anniversary of the D-Day landings?

We could just wish he wasn't coming. But that won't stop him.

He'll enjoy provoking protesters who will, in return, enjoy taking to the streets to taunt him. Maybe the Extinction Rebellion crowd will try to stay camped in trees in Parliament Square until then. He's a better target for their call for action on climate change than a British government that agrees it exists, after all.

But this is pointless. Some first-term presidents have been given one but most haven't, and the difference is more in the title than anything else.

It's not the white-tie dinner at Windsor Castle that people object to. It's the presence of the president himself.

So the question which matters is simply: Should he come here? And the answer to that has to be yes — just as President Emmanuel Macron was right to welcome him to Paris.

We can't pick and choose other world leaders. Diplomacy demands that countries engage, even when the leaders involved are undiplomatic.