There is something soothing about Emmanuel Macron’s state visit to Washington. For three spring days, we are engrossed not in the latest nastinesses surfacing in Donald Trump’s Twitter feed but in weightier things. And lighter too. Things of pomp and tradition. Normal things.

Maybe that’s how it’s been in Britain this week. What better relief from the endless agony of Brexit and the shame of the Windrush deportations than the arrival of a Royal baby? Even those not normally predisposed to the monarchy can relish in the hospital-steps joy just for a minute.

No babies here. Not even a baby elephant, which is what the then president of Sri Lanka gave Ronald Reagan when he passed through town in 1984. Thanks to the Washington Post for its comprehensive list of presents past. My favourites: a stuffed lion ceremoniously presented by Tanzania’s head of state to George W. Bush and crocodile insurance for Barack Obama from Australia. Who told them crocs lurk in the street plumbing under Pennsylvania Avenue?

Some reporter did attempt to disrupt the carefully choreographed Franco-American comity as the two leaders briefly welcomed the press to the East Room of the White House by daring to ask about Michael Cohen, Trump’s personal lawyer who may or may not flip against him after having his office and home raided by the FBI. Trump wasn’t playing. “Stupid question,” he said.

No Cohen today, thank you. (And let’s ignore until tomorrow the drinking-on-the-job rumours about Trump’s personal doctor whom he’s nominated to run the sprawling Veterans’ Affairs department.) We like state-visit rituals much better. They might almost have placed the state dinner menu an on easel in front of the White House. (Only the Brits do that sort of thing.) Et voila: Spring lamb, crème fraîche ice cream and wine from French vines planted in Oregon.

And now we have a new entry into the lexicon of diplomatic watersheds. Nixon invented ping-pong diplomacy to woo China; Trump used dandruff detente to soften the hearts of France. Or may be not. Did you see that — in full Gallic gush he flicks a fleck from Macron’s left shoulder? “We do have a very special relationship, in fact I’ll get that little piece of dandruff off — we have to make him perfect, he is perfect.” Naughty Don. He owned little Macron in that moment.

I did say weightier and the heavy-lifting was for Emmanuel. As the pair went behind closed doors for the “business” part of the visit, we hoped he proved more master than poodle. Trump has gone off the reservation in several areas and Macron had been drafted by European leaders as the only one among them sufficiently attuned to his whims possibly to bend his mind.

The Iran nuclear deal above else. We are closing in on 12 May, the deadline for Trump deciding once more either to renew waivers on sanctions against Iran and thus keep the agreement alive or refuse to do so and kill it, instantly plunging the international community into fresh turmoil. The European argument remains that while the deal isn’t perfect it’s better than no deal at all.

Macron emerged later expressing a willingness to help work on a "new deal" with Iran. We will see what that means but in the meantime Trump will surely keep the world on edge until the last moment as to his final intentions. Certainly, some of his pronouncements alnogside Macron didn't sound encouraging. He called the agreement “terrible”, “insane” and “ridiculous”. And he had a tough response to Iran’s suggestion that it would resume its activities if the deal collapses. “If they restart their nuclear programme, they will have bigger problems than they have ever had before,” Trump said.

Trump seems unimpressed by the argument that he will lose leverage with North Korea if he vapourises the nuclear deal already struck with Iran. He is set to meet with North Korean leader Kim Jong-un, in hopes of striking the outlines of a denuclearisation deal with him, within weeks of decision-day on Iran. The bigger argument from Europe is this: things are so febrile in the Middle East already, why add new uncertainty by giving Iran license to unleash itself again?

“On Iran, we must contextualize this subject within the challenges of the region,” Macron said in the East Room. “There is the situation in Syria, there is security in the entire region and I think, in any case, we share a common goal of avoiding an escalation and proliferation of nuclear weapons in the region. So the question is what is the best path.”

Macron had much besides to tackle, from the viability of the Paris Agreement on climate change so long as the US continues to shun it to concern about Trump’s temptation to withdraw his troops from Syria and European alarm at the 25 per cent trade tariffs placed by the United States on steel imports. All are issues that German Chancellor Angela Merkel will follow up with Trump in Washington at the end of this week though issue number one will be Iran again.

State visits like this one are always a blend of pomp and portent. From frivolous to formal, ritual to wrangle. It will be that again when Macron addresses a joint session of the US Congress on Wednesday. He will note it is the anniversary to the day of Charles de Gaulle practising his oratory on Capitol Hill in 1960. Then he will return to the job of reminding the United States why it must do better in so many ways.