IF bonhomie and backslapping could solve the Brexit backstop crisis, then the solution would have been found over oysters and champagne at the Elysee Palace on Thursday.

Boris Johnson turned up at the French President’s grand pile in a Range Rover festooned with Union flags. Our pugnacious premier, appearing alongside his host at a brief press conference, clenched his fists, gesticulated, nodded firmly and used his favourite phrase “can-do” as he tried to convince anyone who was listening that the necessary “backstop-ectomy” was eminently feasible.

Emmanuel Macron was the charming host, all smiles and friendly winks, but while the diplomatic warmth was on full display, the cold realisation came in the words he used.

The French President sees himself as the guardian of the European Project and will not allow anyone, even his British chums, to do anything that will undermine or threaten it.

His message seemed pretty clear. “The key elements of this agreement, including the Irish backstop, are not just technical constraints or legal quibbling, but indeed genuine, indispensable guarantees to preserve stability in Ireland [and] to preserve the integrity of the single market which is the foundation of the European project.”

While 95 per cent of his remarks were pointing in one direction – Non – there were a small number that will no doubt be seized upon by the Johnsonite optimists as pointing to a possible way through.

Mr Macron insisted that if his two goals – protecting the single market and Ireland’s stability – could be maintained, then the agreement the EU sealed with Theresa May could be “amended”.

But while over-interpreting politician-speak can be easy, it can also be self-delusional.

The President also stressed that trying to achieve a new deal in the 30-day timescale Angela Merkel had spoken of – she later played it down - would not result in anything "very different from the existing one".

Mr Johnson met what seemed to most as the erection of a very large Gallic brick wall with an optimistic determination to immediately scale it, declaring effusively that with “energy, creativity and application we can find a way forward”.

Indeed, the PM believes there is an abundance of measures that can be taken to alleviate the need for the backstop, mentioning trusted trade schemes and the electronic pre-clearing of goods.

However, it is hard to conceive that even if such measures were workable that they would be up and running effectively by in 70 days' time.

EU officials suggested that they expected Mr Johnson to furnish Mr Macron and Mrs Merkel with “full details” of his proposed alternative arrangements when they meet at this weekend’s G7 summit in Biarritz. The PM is due to hold talks with Donald Tusk on Sunday, which should be an interesting encounter given Mr Johnson’s four-page letter to the European Council President outlining why the “anti-democratic” backstop had to go.

Perhaps Jean Asselborn. Luxembourg’s Foreign Affairs Minister, had it right when he noted: "Miracles should never be ruled out but I’m sceptical we can simply pluck something out of the air that guarantees Ireland has no hard border and at the same time the EU has control over what enters its market.”

Mr Johnson ended the Elysee press conference with more vim and verve, declaring: “Where there’s a will, there’s a way.” But it might take more than energy and optimism to get over that mighty brick wall.

During his talks with Mr Macron, the PM was photographed putting his foot on a low table in an expression some saw as Old Etonian arrogance. And when he returned to No 10, our pugnacious premier was snapped seemingly punching the air.

But, of course, victory is not assured. The PM not only has the challenge the EU has set him but also the one closer to home at Westminster. The weeks ahead are likely to prove a baptism of fire that few of his predecessors in Downing St have ever had to encounter.