LONDON — Theresa May can look forward to an excellent dinner at Emmanuel Macron's holiday pad, but she shouldn't expect a Brexit concession for dessert.

Fort de Brégançon, the official retreat of the French president where the two leaders will meet and dine Friday, is a lovely spot, girdled on all sides by the blue waters of the Mediterranean and connected to the mainland by a narrow causeway.

It is certainly worth a visit for the views, the peace and the sea air. But a likely spot for a breakthrough summit on Brexit? Not so much.

Since the Brexit talks began last year, May and her ministers have sought to appeal directly to EU27 member countries — chief among them France and Germany. By going over the head of the European Commission they hoped that national leaders will add flexibility to Michel Barnier’s often rigid, legalistic approach to Brexit.

The recent diplomatic tour of Berlin, Paris and Vienna by new Foreign Secretary Jeremy Hunt, as well as similar visits by other ministers and May herself, fit that pattern. But there is little sign that the U.K.'s latest round of grand tour diplomacy is shifting EU red lines.

Barnier torpedoed May's proposal on market access in the nicest way possible.

“The only negotiation channel is through the EU Commission’s Brexit negotiator Michel Barnier,” said a senior European diplomat, speaking on condition of anonymity. “They will have a political exchange. She will explain to him [Macron] the British position on Brexit, the white paper and the political situation in the U.K. — which deserves an explanation.”

The meeting, the diplomat said, should not be seen as "a political signal."

Ambitious partnership

Barnier is also showing no sign of softening in the summer heat.

In an op-ed published Thursday and titled "An ambitious partnership with the U.K. after Brexit," Barnier torpedoed May's proposal on market access in the nicest way possible. It was the latest in the EU negotiator's continuing effort to make clear that the core of May's proposal is unacceptable to the EU27 without fully rejecting her white paper so completely as to potentially derail the talks or even imperil May's government.

The EU negotiator's strategy has been to praise May's proposals in the white paper on security and foreign policy cooperation, and especially to reiterate the EU27's support for the core idea of a robust free trade agreement as the center of gravity of the U.K.'s future relationship.

"I remain confident that the negotiations can reach a good outcome," Barnier wrote, in one of the few lines to justify his article's optimistic title. "It is possible to respect EU principles and create a new and ambitious partnership."

But most of Barnier's piece was focused on the urgent need for a solution for Ireland and on why core aspects of May's Chequers plan are unacceptable to Brussels because they threaten the integrity of the EU single market. "The U.K. wants to keep free movement of goods between us, but not of people and services," he wrote. "And it proposes to apply EU customs rules without being part of the EU's legal order. Thus, the U.K. wants to take back sovereignty and control of its own laws, which we respect, but it cannot ask the EU to lose control of its borders and laws."

In Berlin too, there was no sign Thursday of a shift in mood music. Germany's outgoing top Brexit official, Peter Ptassek, tweeted out a link to Barnier's op-ed, stressing what has been the EU's top priority in the Brexit negotiations since the start of the year: the need for a safeguard, or backstop, to prevent a hard border between Northern Ireland and Ireland.

And officials expressed surprise that anyone on the U.K. side might have detected a shift in Angela Merkel's tone on Brexit after her July 5 meeting with May in Berlin.

"There hasn't been any change whatsoever," a German foreign policy official insisted.

In fact, Merkel has been at pains ever since the referendum to maintain a consistent position, the official said. In addition to insisting on the sanctity of the EU single market's four freedoms, this also means avoiding statements that could be perceived as either undermining the unity of the EU27 or Barnier's negotiating hand.

Officials in Berlin have also said repeatedly that while Merkel is keen to ensure that Germany's cooperation on foreign policy and security with the U.K. remains intact post-Brexit, the chancellor is not willing to sacrifice core European principles in order to ensure that outcome.

“The Commission is taking a hard line not because it wants to but because it’s got instructions from France and Germany to do so,” said Charles Grant, director of the Centre for European Reform think tank in London. “The British should not assume that just by talking to Merkel and Macron things will get easier.”

EU discipline

Accounts differ as to how Friday's Macron-May meeting came about, and why now. The British prime minister is cutting short her summer holiday in Italy by one day to meet Macron, and is effectively dropping in on the way back to the U.K., to which she is expected to return at the weekend.

The European diplomat said the meeting had been arranged at May’s request and a U.K. government official said the two sides had been trying to get a date in the diary. A French government source told the Times newspaper that it was not a matter of May insisting on the meeting, but that Macron “wished to meet her.”

But Macron is, according to Peter Ricketts, the U.K.’s ambassador to France from 2012 to 2016, “the last person to want to break ranks” with what he called “quite an impressively disciplined EU side.”

France has little to gain from breaking with the EU27/Barnier line.

“We have got to accept we have got to do the hard yards of negotiating in Brussels,” he told BBC Radio 4’s Today program Thursday.

Furthermore, France already has the U.K. right where it wants it in terms of long-term strategic interests, Grant said. The white paper's proposal for the U.K. to follow EU rules on trade in goods, but a more distant trading relationship on financial services (to an extent liberating the City of London to be an even more global force) is fine by the French. They will then position Paris to pick up the future European banking contracts the U.K. will, most likely, sacrifice under such a setup.

And on defense, that other strong card of the U.K., Paris is confident, Grant said, that its interests are already secured through bilateral and multilateral, (but, crucially, non-EU) structures like the combined U.K. and French Joint Expeditionary Force and the recently signed European Intervention Initiative, which Macron spearheaded.

Neither structure depends on the U.K. getting a generous Brexit deal — so France has little to gain from breaking with the EU27/Barnier line.

This does not leave the U.K. entirely without leverage. While these military structures are outside the remit of the EU, a truly hard Brexit — the no-deal scenario that Hunt warned of in Berlin, in Paris and in Vienna — would be so disruptive it could shake bilateral relations between France and the U.K., Grant said.

“I guess what Mrs. May will do is say 'look, if you really screw us, really give us a bad deal, that would lead us to go downhill economically; is that going to create the climate whereby geopolitically it calls into question the relationship with the French or the EU on security?'” he said.

“Hunt has half a point. A bad, acrimonious Brexit has geopolitical implications and the French understand geopolitics much more than any other member state does.”

It’s a risky game to play though. The prevailing wisdom among diplomats in Paris, Berlin and Brussels is that the U.K. has more to lose than the EU from a no-deal scenario. But in this game of Brexit poker, it is one of the only hands the U.K. has left to play.

Maïa de La Baume and Matthew Karnitschnig contributed reporting.