The Special Relationship is British Soft Power

"Ladies and Gentlemen, POTUS has left the country."

Not quite the radio call delivered to the army of civil servants, security details and protocol officers who made this visit happen. But there was, no doubt, a collective sigh of relief from both Team Trump and Number 10 that this epic diplomatic circus - with its hundreds of moving parts - landed far better than many dared hope.

The additional pomp and ceremony paid dividends for a President who thrives on flattery. And it worked. The visit rekindled fresh vim in that much-used phrase, "the special relationship" - too often dusted off to justify a bond forged in war, rooted in a shared commitment to defend values and norms beyond our shores.

That bond is often judged through the prism of personal chemistry: Churchill and Roosevelt, Thatcher and Reagan, JFK and Macmillan, Blair and Bush. There is truth in this. But with Trump, it is clearer than ever that the Royal Family has been the quiet constant - binding our nations together with dignity and symbolism, when politics falter. The King now follows in his mother's footsteps: using ceremony, symbolism and regal diplomacy to personalise national bonds and give the UK government's agenda extra weight.

Yet Donald Trump is no typical American President. More populist, nationalist and isolationist than any of his predecessors, Trumpism has rewritten America's relationship with the world - retreating from the duty of upholding global order at precisely the moment it looks most fragile.

Isolationism, of course, is not new in American thinking. George Washington cautioned against entangling alliances after France sought US support in its own revolution. A century later, America hesitated before entering both World Wars - stepping in only when neutrality proved impossible.

Trump's instinct to pull back from global responsibilities, then, is less an aberration than a revival of an old reflex. But history also reminds us: when America stands back, disorder rushes in. And today is not the time for retreat. That is why you do not squander two days of face time. Whatever one thinks of Trump personally, as US President his decisions ripple across the globe. America has usually welcomed Britain's counsel on world affairs - but few leaders dare push back against Trump, let alone stand up to him. After laying on this second state visit, Britain has earned that rare distinction. We must harness it.

For these are increasingly turbulent times, as another 'ism' makes its mark: Xi-ism - the fusion of authoritarian control, nationalist revival and state-directed capitalism under Xi Jinping. It combines strict Party dominance at home with an assertive China abroad, driven by a desire to re-write the global order in Beijing's favour.

If Xi-ism is to be prevented from dismantling the post-war system that once tethered the world to liberal democracy, then Trumpism must evolve. America and Europe must be on the same page. The penny is slowly dropping: Putin is not our friend, NATO is worth standing by, and our rules-based order is in trouble. But time is running out.

China is already leveraging its soft power on a staggering scale to construct a rival global order. With over 100 countries now tied into its Belt and Road infrastructure programme, Beijing is well on its way. The world risks splintering into two spheres of influence - with many nations forced to take sides.

Until we repair the global order, that trend will continue - edging us ever closer to conflict. We need America's help to fix it. The UN is paralysed by the veto. The WTO is broken, with Washington refusing to honour its appeals process. The IMF and World Bank, underfunded and unsure of mission, struggle to keep pace. It falls to Britain, once again, to help America step up. The Special Relationship carries that duty. If we shirk it, we are all in trouble.