20/04/2016 04:01 BST | Updated 20/04/2017 06:12 BST

Trying to Gag Obama on Brexit Betrays British Values

On Thursday, in his last full presidential year, President Obama arrives in Britain on a farewell tour of some of America's closest allies. He will have just come from meetings with the monarchs of the Gulf Arab states. After London he travels to Germany to meet Europe's most powerful leader, Chancellor Merkel.

For those in Britain, eternally fearful of our decline as a world power and forever examining for signs of decay the so-called special relationship with America, this should be gratifying confirmation that we still sit alongside the US at the top table of international politics.

But nowadays there is nothing particularly special about the relationship. In his cool, detached way, Obama has never bothered, as did Bill Clinton and George W. Bush with Tony Blair, to foster the illusion of Britain as the indispensable link beween America and Europe. For several years Obama gave Britain a kicking for not meeting the NATO requirement that members spend 2% of national output on defence. We are told that he even threatened David Cameron with the demise of the special relationship if we did not cough up - which we duly did. The Americans have always known that they have only to invoke this venerable Churchillian relic and, like Pavlov's dogs, we will jump to attention and salute.

Earlier this year, Obama made a disparaging reference to Cameron's loss of interest in Libya after Britain, with France and the US, had in 2011 helped overthrow the Libyan leader, Muammar Gaddafi. That had led to his assassination and Libya's descent into a chaos which is now being exploited by ISIS. Obama's rebuke was greeted over here by howls of anguish and front-page headlines. Never mind that there was more than a grain of truth in his criticism of our prime minister, and that other close allies felt the lash of Obama's tongue.

For those who believe, as I do, that the US remains our most important ally, Obama's visit is the moment to pump some red corpuscles into a relationship, more anaemic than special. And that might have happened in normal times. But these are not normal times. In truth, the President's visit risks making a scratchy relationship scratchier. If that happens, Obama will turn with relief to Angela Merkel and the Germans.

On arriving in London he will find himself thrown into the monstrous hopper of the British referendum campaign, where facts are sacrificed daily on the altar of propaganda and abuse. He has been insulted by the leading Brexiteer, Boris Johnson, for suggesting that the United States would prefer Britain to remain in the EU - declared, bipartisan, American policy since time immemorial. A group of Eurosceptic MPs have warned him off intervening in the campaign.

Yet, for all the fog of the Brexit wars, Obama's visit will vividly illuminate what is at stake for Britain on 23 June. The referendum will fix Britain's place in the world for a century or more. It will decide the nature of our relations not only with the European Union, but with all our close allies and partners beyond Europe, foremost among whom is the US.

These allies and partners have every right to express a view on Brexit. Their histories and national interests are intimately entwined with ours, from Japan with its billions of pounds invested in our car industry, to the US with its indispensable contribution to our security. What is a special relationship worth if the American president is not allowed to say his piece on Brexit? The US national interest is profoundly in play. When the American ambassador to Britain tells us that Washington wants a strong UK in a strong EU, it may be a trite phrase, but it rests on 75 years of intimate American engagement with Europe and Britain. Obama may have proclaimed a "pivot to Asia". But Europe remains an area of vital American interest, with a revanchist Putin on the march.

If nothing else, this visit may snap us out of the misty sentimentality with which we continue to view the idea of a special relationship with the US. Like any other relationship between states, it's about hard national interest not sentiment, though in the case of our two countries interests converge more often than not.

President Obama is, let us not forget, the leader of a country which saved our bacon in World War 2, kept Soviet Russia at bay during the Cold War and today provides 70% of NATO's military muscle. We should afford him the freedom of speech that we ourselves profess to uphold. So, can we, please, mind our manners and not abuse the President during his visit? If that is not a British national interest, I don't know what is.