Boris Johnson has failed to rule out resigning from cabinet this year at the end of a speech aimed at reassuring worried Remainers that veered into jokes about dogging, sex-tourism and stag do's.
The Foreign Secretary, appearing to ad-lib through large sections of his address, said the UK should stick to EU regulations only where it chose to.
Mr Johnson used his speech, the first in a series of set-pieces by cabinet members, to insist that "Brexit can be grounds for much more hope than fear".
He said it would be a "disastrous mistake" to stop Brexit, which would "lead to permanent and ineradicable feelings of betrayal", adding: "We cannot and will not let it happen."
People had concerns about the strategic, "spiritual" and economic consequences of Brexit, but whatever the "superficial attractions" they could be "turned on their head".
"Brexit need not be nationalist but can be internationalist; not an economic threat but a considerable opportunity; not un-British but a manifestation of this country's historic national genius."
Mr Johnson insisted that Britons would continue to be able to live, work and retire in the EU after Brexit.
"If we get the right deal on aviation and on visa-free travel - both of which are in our mutual interest - this expansion of UK tourism will continue, not just beyond the EU but within the EU itself," he said.
"There is no sensible reason why we should not be able to retire to Spain.
"For those who really want to make Britain less insular, the answer is not to submit forever to the EU legal order."
Mr Johnson also repeated his call for another crossing for the English Channel.
He said: "Brexit is about re-engaging this country with its global identity and all the energy that can flow from that. I absolutely refuse to accept the suggestion that it is an un-British spasm of bad manners.
"It's not some great V-sign from the cliffs of Dover, it is the expression of legitimate and natural desire to self govern of the people, by the people, for the people.
"That is surely not some reactionary Farageist concept."
Answering questions following the speech, Mr Johnson said he fully supported the Prime Minister's Brexit policy as set out by her at Lancaster House and in Florence, but did not respond when asked whether he would leave the cabinet to challenge Theresa May's leadership.
Labour MP Chuka Umunna, a leading figure in the Open Britain campaign to stay in the EU single market, said: “This was an astonishing exercise in hypocrisy from Boris Johnson. His vision of Brexit may be many things, but it is not liberal.
“His plan would see Britain sever trade ties with our largest trading partner, weaken protections for workers, consumers and the environment, and jeopardise the Good Friday Agreement in Northern Ireland, a subject he didn't even bother to mention.
“The scaremongering, mistruths, lack of detail and utter disregard for the economic realities of Brexit were an alarming throwback to the referendum campaign. More than 18 months since the referendum, this was simply more of the same Project Fantasy."
The Liberal Democrat Brexit spokesman Tom Brake said Mr Johnson was “completely deluded” and had failed to offer any substance or reassurance.
“This speech wasn’t about the most important issue facing our country right now, this was about Boris’ ambitions to become the next Prime Minister, and it probably wasn’t much help on that front either,” Mr Brake said.
“The lack of detail and understanding shown in this back of a fag packet speech would be astounding, if we didn’t already know that the government has no clue and no plan.
“As ever, Boris managed to find time to practice a dead language but failed to tackle the live issues.”