France has boasted to City of London chiefs that it will use Brexit to sabotage the British economy, according to a bombshell leaked memo.

The memo, sent to Ministers, says the French government and banking chiefs are plotting to ‘actively disrupt and destroy’ the UK’s multi-billion-pound financial sector when Britain leaves the EU – even if France gains nothing.

The missive blames the ‘giddy’ effect of newly elected President Emmanuel Macron for an ‘assertive collective endeavour’ to wreck the City, which is worth £66 billion a year to the Treasury in tax receipts – around half of the entire budget for NHS England.

The 'giddy' effect of newly elected Emmanuel Macron is said to be blamed for the new French plot to 'actively disrupt' the City

The memo was written after the City of London’s Brexit envoy – former Home Office Minister Jeremy Browne – held talks in Paris earlier this month at the French finance ministry, state-owned Banque de France, the French Senate and the British Embassy. He met banking chiefs, senior politicians and diplomats.

His message to UK Treasury Ministers and MPs says Macron’s France has effectively declared open war on London’s Square Mile. And he warns starkly: ‘They are crystal clear about their underlying objective: the weakening of Britain, the on-going degradation of the City of London.’

He pointed to ‘French representatives crashing around London’ offering big sums to firms to move to Paris.

French finance minister Bruno Le Maire was appointed by Mr Macron earlier this year after being lauded for saying Brexit provided a ‘fabulous opportunity for France’. And the country’s banking bosses are just as belligerent, says Mr Browne.

He writes: ‘The meeting with the French Central Bank was the worst I have had anywhere in the EU. They are in favour of the hardest Brexit. They want disruption. They actively seek disaggregation of financial services provision.’

The City of London’s Brexit envoy Jeremy Browne (pictured) has warned UK Treasury Ministers that Macron’s France has effectively declared open war on London’s Square Mile

Reinforcing his warning, Mr Browne says: ‘The clear messages emanating from Paris are not just the musings of a rogue senior official in the French government or central bank. France could not be clearer about their intentions. They see Britain and the City of London as adversaries, not partners.’ The memo suggests that other EU nations who wanted good relations with the UK over Brexit were alarmed by France’s hostile conduct but were powerless – or unwilling – to stop them.

Mr Browne says: ‘There is plenty of anxiety elsewhere in the EU about the French throwing their weight around so aggressively, but their destructive impulses are not being confined, and other EU countries that want a friendly relationship with Britain and the City of London are being marginalised.’

The memo states that the 'on-going degradation of the City of London' is a key objective for French bankers and politicians

The French were ‘commendably honest about their true intentions – which makes the exchanges more meaningful.’

Mr Browne even hints they were acting out of spite, ‘making a virtue of rejecting a partnership with Britain and happy to see outcomes detrimental to the City – even if Paris is not the beneficiary’.

Make no mistake, he warns, France sees the UK and the City ‘as adversaries, not partners.’

HYSTERICAL? NO, I STAND BY MY 'APPEASEMENT' WARNING Comment by Andrew Adonis, Labour Peer Hysterical. Over-excited. In need of therapy even. As extreme as it was predictable, this is how I was labelled by arch-Brexiteers after I warned that quitting the EU could be Britain’s worst mistake since the 1930s appeasement of Hitler. No reasoned argument, no carefully calibrated response… just the implication that I had taken leave of my senses by making a comparison with those dark days leading up to the Second World War. But I stand by every word. To recap, I warned that if badly handled, Brexit could lead to this nation’s greatest blunder since appeasement because it could have such a dreadful effect on our people. A blunt, ideologically driven break with Europe could lead to millions of Britons being thrown into poverty – made worse by the fact that in last year’s referendum, they were sold false promises of a new dawn. Adonis: I was saying that a botched Brexit would have such huge ramifications that it could only be compared to our misguided appeasing of Hitler By invoking the era of appeasement, I was not trying to depict Theresa May as some latter-day Neville Chamberlain or, as Margaret Thatcher’s official biographer suggested, portray Jeremy Corbyn as a modern-day Winston Churchill. I was saying that a botched Brexit would have such huge ramifications for ordinary working people that it could only be compared in the sweep of British history to our misguided appeasing of Hitler. I confess to having been a long-time supporter of British membership of the EU since my student days. But unfortunately for my Brexiteer critics, I do not fit the identikit photo of a swivel-eyed Brussels obsessive. My political career has been almost entirely spent tackling challenges nearer home. For 20 years I have been on a mission to improve England’s education and transport systems, which were bywords for failure and poor service. I left the EU for others to worry about. But ahead of a Westminster debate on the subject, I buried myself in the House of Lords library and underwent two weeks of immersion in the details of the EU’s customs union and single market to understand what they meant for British jobs and trade. It was a Damascene conversion. I already feared that Brexit – or hard Brexit at any rate – was unwise and risky. But I discovered it was extreme, dangerous folly; and that any Brexit which involves leaving the central economic institutions of the EU will imperil millions of jobs. It would make us the poor relation of France and Germany for as long as we remain isolated. It is not just that hard Brexit involves imposing tariffs on our trade with Ireland, France, Germany and the other 24 EU states, which between them account for 44 per cent of our exports. There is the enormous practical issue of imposing customs controls, including border checks, on so much trade that previously flowed freely. As for ‘Empire 2.0’ – the supposed riches of trading with the English-speaking world – the EU’s trade treaty with Canada took effect just two weeks ago! If you take all 75 nations covered by the EU’s existing trade treaties, they account for 18 per cent of British exports over and above the 44 per cent going to the EU 27. That’s more than 60 per cent of exports going either to the EU or to countries beyond, made possible by our customs union membership. So, before a single kilo – sorry, ounce – of new trade can be secured, David Davis and Liam Fox have first to negotiate a trade treaty with the 27 remaining EU states, no less favourable than the existing customs union. Then they must negotiate deals, also no less favourable than the EU’s existing deals, with a further 75 countries. All in the next 20 months. Dream on! The challenge of the next decade and beyond is to prevent Brexit from consuming the jobs and livelihoods of millions of hard-working Brits. So whatever the brickbats and insults aimed at me, I will not move from my warning. Advertisement

It was much more serious than the wily French merely putting down a Brexit talks marker as ‘the opening shots in a long negotiating process,’ says Mr Browne.

French industry was barely more conciliatory than French finance and banking, and offered no ‘life raft’ for Britain. They were ‘by a big margin, much worse than the norm elsewhere in the EU’.

Observing that it was Wimbledon fortnight, Mr Browne says the Government must do more to combat the French threat by ‘putting some more balls back on the other side of the court’.

Diplomat’s son Mr Browne, 47, was a Lib Dem Minister in David Cameron and Nick Clegg’s Coalition, serving in the Foreign Office and Home Office. He campaigned for Britain to stay in the EU but was seen as a Lib Dem Eurosceptic and supported cutting the top rate of tax. It led to reports that he was considering defecting to the Conservatives.

French finance minister Bruno Le Maire (pictured right) said earlier this year that Brexit provided a ‘fabulous opportunity for France’

He became the City of London Corporation’s Brexit envoy on a six-figure salary after losing his Commons seat in 2015. The jet- setting job has taken him to 26 EU countries in 18 months to ‘make sure the City’s voice is heard’ before Brexit.

Financial experts say the City is particularly vulnerable to the disruptive effects of Brexit, with knock-on effects for the rest of the economy. Nearly 12 per cent of the UK’s tax revenues come from the financial services industry, which employs more than seven per cent of all UK workers.

It has been claimed the banking and financial services sector could lose tens of thousands of jobs as a result of Brexit.