The high profile Brexiteer was reportedly close to leaving the Conservative Party following months of bitter infighting among Tory ranks about how close the UK’s relationship to Brussels should be.
An ally of Mr Johnson said the foreign secretary was concerned Mrs May was leading the UK towards a soft-Brexit where the nation would still be shackled by EU laws.
A friend told the Sunday Times: “It was a very long and torrid day.
“For much of it he thought it was going in totally the wrong direction. He thought there might be a long walk home.”
The Brexit sub committee met for eight hours at Chequers where the senior members of the cabinet thrashed out the plans for the future relationship with the EU.
Ahead of the meeting, one Cabinet source said: “Hammond and Boris are still the two on the peripheries of the argument, and both are still very dug in.
“It doesn’t look like either are ready to budge yet, so some sort of verbal fudge looks most likely.”
However, after a long day of debates, which saw discussions continue over a dinner of sweetcorn soup, Guinness rib of beef, and dessert lemon tart and raspberries, it is believed an agreement for divergence was struck.
Boris Johnson issued a Brexit ‘red line’, where he insisted the agreement of divergence must not be watered down because it allows innovation in the British market.
Ministers agreed Britain would diverge from EU laws, however pledged to maintain high standards, or voluntarily opt into EU laws.
A source said: “Boris makes no distinction between the offer and our bottom line.
“This is what we must get.”
Pressure has been building on the Cabinet to come to a unified position on Brexit, with Tories split over how to lead the country out of the bloc.
Remainers back closer ties with the EU, while leading Brexiteers want Britain to be unshackled from the stringent rules and regulations of the bloc.
But during a meeting at Chequers a compromise agreement was struck after the Prime Minster “played a blinder”.
The group agreed Britain must not be part of a customs union and that frictionless trade was still possible without one, it has been reported.
Britain is expected to propose a deal whereby industries with cross-border supply chains will stay closely but voluntarily aligned with EU rules.