If anybody cares to doubt the extent of France’s efforts to encourage City firms to flee Brexit for Paris, they should talk to our financial services chief executives.

Not just the bosses of HSBC, Bank of America Merrill Lynch, BlackRock, Citigroup and Goldman Sachs, who have already agreed to expand their operations there, but the ones still considering their options.

One such FTSE-100 chieftain recently told of how he was stunned at the extent the Macron government was prepared to go to lure his business across the Channel.

He and a handful of fellow City capos had just returned from Paris where they were hosted by Bruno Le Maire, the French finance minister.

In a grand room of the Elysée Palace, Philip Hammond’s oppo gave the clear impression he would do almost anything to get them to move there.

Le Maire — a man with no small workload — spent the large part of a day with them, painstakingly laying out how France was liberalising its financial services environment.

He listened to their concerns and reassured them, in detail, that the Macron administration was dealing with them.

“He wanted British business and wasn’t being subtle about it,” said the Footsie boss.

Today, the FT reports that Hammond is privately warning that France will up its efforts to win UK business by making it harder for City firms to access European markets after Brexit.

Not immediately — the disruption would be too great for French companies — but in the coming years, Paris will lead moves to develop regulations that will bind City-based firms like creeping ivy.

Hammond is absolutely right: the pro-business corners of Paris have long coveted the City’s dominance of global finance.

While France has hobbled its banks’ growth with decades of socialism, London’s financial services industry has grown to a position where it now contributes £35 billion a year in taxes to the UK treasury, half of which is from non-UK firms.

Macron’s camp see Brexit as the biggest opportunity since Big Bang for France to get a share of that booty.

And why wouldn’t they? Britain is spectacularly shooting its most lucrative industry — finance — in the foot by leaving the world’s biggest trading bloc, removing one of the key reasons international firms base themselves here.

Now the hardcore Eurosceptics seem intent on exacerbating the damage by pushing for a no-deal departure that would make us even less attractive as a financial hub.

They think international banks and insurance companies will never move from the City.

Instead, they will push their services to exciting new emerging markets in Asia and Africa.

Perhaps Brexiteers haven’t noticed, but — as figures from HSBC show today — our financial firms are already there.

A no-deal Brexit offers only negatives for the City.

The positives will be enjoyed by London’s rivals on the continent.

Just ask Bruno Le Maire.