The Prime Minister issued the threat as the EU’s negotiations boss, Michel Barnier, put forward a series of terms that the UK must meet should it want to secure a trade deal with the EU. This agreement must be made and come into force at the end of the 11-month long transition period, which ends later this year - exactly on December 31.
Failure to reach an agreement would result in both the EU and UK facing unfavourable trade quotas and tariffs on exports.
In what has been described by allies as a “mad man” move, Mr Johnson flashed his teeth and buffed up the UK’s Brexit stance.
He said: “We have made our choice; we want a comprehensive free trade agreement, similar to Canada’s.
“But in the very unlikely event that we do not succeed, then our trade will have to be based on our existing Withdrawal Agreement with the EU.
“The question is whether we agree a trading relationship with the EU comparable to Canada’s – or more like Australia’s.”
The latter reference to an Australian style agreement has largely been interpreted as a threat for no deal at all.
Australia currently only trades with the EU on World Trade Organisation (WTO) terms with hefty tariffs.
Despite the Prime Minister’s attempts at flexing his post-January 31 muscles, many viewed the move as being in the wrong direction.
Explaining his seemingly hard line stance, one ally said it was a “mad man” strategy similar to that of Mr Johnson’s attempts to broker a deal with the EU five months ago.
Now, however, time is of the essence, and the source worried over the rhetoric in play.
They told The Sun: “Will he walk away? You just never know. That is what we want the EU to wonder, and that is what worked last year”.
In a symbolic move on Monday, Mr Johnson choose the Old Royal Naval College in Greenwich to lay out his vision of a free-trading Britain after Brexit.
He also revealed that he has ordered negotiators to explore multiple trade deals simultaneously.
Lapping even more pressure on the EU, he said his government is “ready for the great multi-dimensional game of chess in which we engage in more than one negotiation at once”.
International Trade Secretary Liz Truss will lay out Britain’s negotiating plan for a US trade deal later this week.
Talks will also shortly open with Japan, as well as Australia, New Zealand, Canada and Commonwealth countries.
Controversially, Mr Johnson has already set out that he has no plans to agree with the EU in its demands for a level playing field of rules for government.
Some of these rules span from workers’ rights, environmental standards and state aid for failing companies.
He called it “an absurd caricature” to suggest that Britain would “engage in some cut throat race to the bottom”, and argued that the UK’s standards are often superior to the EU’s.
Mr Johnson scoffed: “As if it was only thanks to Brussels that we are not preparing to send children back up chimneys.”
Instead, the Prime Minister said the UK is willing to sign up to global stands in all policy areas.
These would be along the lines of what Canada or Japan had agree with the EU in their deals.
Boris also ruled out granting the EU permanent access to the UK’s fishing waters – another key Brussels demand laid out Monday – and decreed there would be annual talks to set quotas for Europe’s boats instead.
The PM insisted: “British fishing grounds are first and foremost for British boats.”