Sometimes I see the point of a king. Imagine if it had been Boris Johnson standing under the Arc de Triomphe this week, telling the French president, Emmanuel Macron, “Donnez moi un break.” Imagine Liz Truss telling Versailles “the jury’s out” on her opinion of France. There are moments in relations between nations that require the presence of heads of state – however chosen – that are not party politicians. When one is the other, as with the US’s Donald Trump or even occasionally with Macron, it can turn sour. Britain’s recent relations with France have been a shambles. They have lurched from rows over fishing quotas to rows over Northern Ireland, Pacific submarine contracts, residents visas, asylum seekers and people smugglers. The result of Johnson’s sabotage of Theresa May’s soft Brexit was to reduce the Port of Dover to chaos, and to have Macron asking if Britain was governed by circus clowns. Clearly France has much to answer for in its handling of the refugee crisis that plays out between the two countries. Walk the beach of adjacent Belgium, and you will hardly see a single boat of asylum seekers. A mile down the coast in France is mayhem, despite £63m in UK subsidy laughably donated to the French police. This, of course, has nothing to do with the king. But it does have to do with the respect that these two countries have for each other, and whether they can share problems and find advantage in that sharing. Soft power is not powerless, not even that of a king. The deep affection Edward VII had for France played an important part in forging the Entente Cordiale, before the first world war. Britain is currently and obviously suffering the consequences of Brexit. Westminster politicians encouraged it with a childish hostility and contempt for Brussels and other European states throughout the 2016 campaign. When I heard Brexiters jeer that Europe needed Britain more than Britain needed Europe, I wondered what horror lay in store. Now we know. By 2019, Paris had overtaken London as top European destination for foreign tourists, and has stayed there. People do not like being made to feel unwelcome. Kings are not elected to delve into these matters. The issues of people-smuggling and trade friction are for Macron to resolve with the British government. The same must apply to this week’s Franco-German proposals for a multitiered EU, a possible slow road for Britain back to a more constructive relationship with Europe. These matters will ultimately depend on cooperation between French and British elected politicians in elected assemblies. Charles has no particular special insight into the realms of French policy, nor should he. He is known to have serious interests, not least for the environment and for cultural promotion. It cannot be wrong for these interests to be shared with Macron, and we assume that Macron can choose for himself whether to listen. Elected politicians do, however, listen to public opinion. Their skill supposedly lies in taking temperatures, in knowing how best to pander to the popular mood. According to YouGov, following Brexit, the percentage of French people taking an unfavourable view of the British surged from 33% to 42%. The British view of the French moved likewise. On the other hand, the French have always had a soft spot for British royalty. According to Le Figaro, 71% of the French public are “in favour” of the British monarchy. Seven million watched the Queen’s funeral on French television channels, with a 66% audience market share. This cannot be of no account. For millions of Britons, too, Charles is a popular monarch who has taken up the reins of office with skill. Merely to have visited France this week and passed on copious compliments will have pleased the French. It suggests a friendship and respect contrasting with the hostility shown so frequently in Westminster. Where royalty has public opinion on its side, all is well, and there is no reason why it should not be exploited for the benefit of the state. Britain at present has every interest in being on the best possible terms with France. France’s constitutional structure may be different from Britain’s, though its local democracy is glaringly superior. Given the shambles that is now British local government there is hardly a town I would not swap for one governed and planned in France. At least until Brexit, a third of Britons were visiting France every year, and it would be sad if this degree of contact were to stop. The next decade for Britain could involve a bumpy road back to a more collaborative relationship with its continental neighbours. On that road, it will need France by its side. That means being nice to the French. If Britain’s politicians are still too frightened or too xenophobic to get this point, at least there is a king to understand. Simon Jenkins is a Guardian columnist