Using the artificial exchange rate called Purchasing Power Parity (PPP), the French economy comes out about level with the UK. But the French population is slightly smaller than the UK’s so at PPP rates France’s GDP per capita is slightly higher than the UK’s.

What’s more, over recent decades, France has more than held its own against its neighbour, Germany. Both analysts and people at large speak and write as though the German economy is a colossus, yet the French economy is less than 30pc smaller.

It is probably in productivity that France provides the greatest surprise. Productivity per hour worked is slightly higher than in Germany, and about 20pc above the UK’s level. So the French are clearly doing something right.

This performance is all the more surprising given that from an Anglo-Saxon economic perspective, France does just about everything wrong. 

It has a huge state sector, with a corresponding tax-take, amounting to 47pc of GDP, which is high by international standards; the government regularly intervenes in the working of the economy; the country is a closet protectionist against foreign suppliers; and the workforce is militant, with a high number of days lost to strikes.

So, given all this, how come that France does so well? Over the years I have proffered a number of possible answers, although I do not find any overwhelmingly convincing. 

One of the best, I think, is that France is a naturally robust country, blessed with a rich and varied environment and a wonderful agricultural base, beautiful old towns and countryside, making it, amongst other things, extremely attractive for domestic and foreign tourism. 

With a country like this, a government has to do something very wrong indeed to send it down the tubes. By contrast, the Netherlands and Singapore, for example, are fragile. There, prosperity has to be wrenched from less forgiving circumstances and policy errors show up sharply.

Another possible explanation that I think holds some water is that both French bureaucrats and French business leaders are extremely able – and especially able at getting the best results for the country, even when government policies and behaviour are against domestic interests.

A possible explanation that I have heard advanced by others is that France’s closet protectionism is at the root of its success. But I cannot believe this is true. Across the world, protection protects the inefficient and hurts consumers. I cannot see how France is an exception.

I have always thought that a large part of the answer is that it takes a long time for a country like France to be knocked off balance but that the reckoning has been postponed, rather than avoided. It is still yet to come – but it is on its way.

There are clear signs of underlying problems. Perhaps one of the most serious is the huge number of French people who work abroad, as many as 250,000 in London alone. They have fled high taxes, an anti-business culture and a rigid labour market.

Given those characteristics, high French productivity has an adverse element. Although unemployment fell during Macron’s first term, at 7.4pc, it is still very high. Here in the UK it stands at only 3.8pc.