The Foreign Secretary, who spearheaded the Brexit campaign, apparently told Brussels ambassadors that uncontrolled immigration “corresponds to his own beliefs” and that Britain had benefitted greatly from EU migrants.
At least four EU officials who were at a lunch with Mr Johnson last month confirmed tonight that he made the remarks, with one blasting that he now has “no credibility”.
And top europhile Nick Clegg, whose Lib Dem party is fighting to keep Britain in the Brussels bloc, said Leave voters would feel betrayed by the ex Mayor of London”s remarks.
The leaked comments are likely to infuriate Theresa May, who has repeatedly stated that regaining control of Britain”s borders will be her top prioritiy in negotiations with Brussels.
Mr Johnson repeatedly bellowed the Leave campaign”s chief slogan that Britain needed to take back control of its borders as he toured the country to drum up support for Brexit ahead of the June 23 vote.
At one rally he asked a cheering crowd: “Isn’t it time we took back control of our immigration policy?”
But tonight senior EU ambassadors told Sky News that the Foreign Secretary has been making very different remarks about Europe”s freedom of movement policy in private.
One revealed: “Boris Johnson told us he was personally in favour of it, but he said that Britain had been more affected by freedom movement of people than other EU member states.”
Another added: “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.”
And a third official said: “Boris Johnson has been openly telling us that he is personally in favour of free movement.”
Reacting to the revelations Mr Clegg, the Lib Dem”s EU spokesman, said Brexit voters had a right to feel “angry” that Mr Johnson had made the remarks and accused him of “taking voters for fools”.
He blasted: “It just suggests that Boris Johnson, one of the senior members of this Government, is just treating voters like fools.
“Boris Johnson was the figurehead of the Brexit campaign, he was the principle spokesman of their key message which was that they would bring an end to freedom of movement, and if it now emerges that he never believed it all along I think it will leave a lot of people who voted for him and for Brexit extremely angry indeed.”
Mr Clegg said the remarks made the Government look “incoherent in its approach to Brexit” and said they had made Britain look “very silly and a bit bizarre in the eyes of many other capitals around Europe”.
He raged: “Of course we’re used to the fact that Boris Johnson said one thing before the 23 June and another thing after.
“But what sets this apart is this was the fundamental, the corner stone, the principle proposition put to the British people by him more than almost anyone else.
“The Brexit campaign was very vague and opaque…but the one thing they were very, very clear about to a man and a woman was that we would end freedom of movement by leaving the European Union.
“This was such an axiomatic thing that was constantly told to us by Boris Johnson and now it appears he never believed in it all along.”
The remarks will prove a huge embarrassment to Mrs May, who is trying to impose some kind of message cohesion on her warring Cabinet, and will only further undermine her negotiating position with other EU leaders.
Eurocrats are bound to pounce on the unguarded comments to argue that Britain should accept continued freedom of movement in return for staying in the single market, guiding the country towards a Norway style deal.
The blunder is not the first time Mr Johnson, who was a controversial pick for Foreign Secretary, has strayed from the official Government position over Brexit.
Earlier this month he had to be reprimanded by Number 10 after hinting that Britain was set to leave the Customs Union, despite Downing Street insisting no decisions on the UK”s future trading relationship with Europe have been taken.