In his first major policy address since taking office, Johnson argued that U.S. President-elect Donald Trump has a valid point about North Atlantic Treaty Organisation members needing to contribute more to the cost of their defense.
Sky News on Wednesday quoted four ambassadors as saying Johnson privately told them he supports freedom of movement, despite leading a campaign that made ending mass migration a key issue ahead of the June referendum on European Union membership.
"The foreign secretary said what he has said many times before - he is pro immigration but wants to take back control to limit numbers", the source said.
Europe must heed Donald Trump's call to increase defence spending, Boris Johnson warns - as he says Russian Federation and Islamic State are making the world a more "brutal" place.
Speaking under the Chatham House rules, which allows comments to be reported but not attributed, one ambassador said: "He did say he was personally in favour of free movement, as it corresponds to his own beliefs. But he said it wasn't government policy", a third ambassador reportedly told the news outlet.
May has said she plans from the jurisdiction of EU law and from the judgments of the European court, and use Brexit as a springboard for Britain to agitate global free trade and negotiate new deals.
"It is stupid to say that freedom of movement is a fundamental right". According to The Guardian, the comments were made during a private breakfast meeting in October.
So the damning testimony of four European Union diplomats appears to suggest Boris Johnson - who attacked the principles of freedom of movement on the referendum campaign trail - is deviating from collective responsibility in private.
Boris Johnson will issue a warning that democracy is in retreat across the world and that a "cult of the strongman" is taking hold, raising the prospect that the concept of a global liberal order will fade into irrelevance.
Johnson's comments about collective defense are also created to reassure European nations that Britain remains committed to the security of the region even as the country prepares to trigger its official withdrawal from the 28-member European Union by the end of March.
"This is the year when - as we periodically do - we did something that startled our friends and rivals", said the Foreign Secretary. "This puts huge pressure on schools, hospitals and housing".
He also refuted claims that he told four ambassadors that he favoured the free movement of people, which was revealed on Wednesday.
A close ally in the campaign said it was "very unlikely" he would express support for free movement. "If they still can not agree amongst themselves what Brexit means after five months, how do they expect to successfully negotiate a good deal for the British people?" Rather than turning its back on the world, the post-Brexit country must be "more outward-looking and more engaged with the world than ever before", he said. "Day by day, more inconsistent fragments of the government's non-strategy for Brexit are slipping out".