If a time traveller from the mid-20th century had suddenly arrived in London on Monday, they might have learned some alarming facts about Britain. In his first major speech since we left the EU, the prime minister eulogised the country’s “newly recaptured powers”, declared we were “re-emerging after decades of hibernation as a campaigner for global free trade”, and revealed we would “reach out to the rest of the Commonwealth” and “engage with Japan”. How had Britain isolated itself from free trade? Why had it been unable to do business with its international friends? What dastardly power had colonised the mighty UK?

The truth was, of course, more prosaic. The UK in fact pioneered the EU’s single market, the world’s deepest and most comprehensive transnational trade zone, and has now elected to replace it with commercial barriers. Japan signed a trade deal with that market in 2018. And the EU has engineered such a brake on Commonwealth trade that in 2018 Germany exported 125% more to India and 100% more to Australia than we do. The only cage to have imprisoned the UK is one of its own hubristic making.

The policy has not changed, but the words have. A Foreign Office memo this week confirmed the government’s new approach. Officials may no longer use the terms “deep and special partnership”, or refer to the”‘implementation period”. The outcomes on offer are either “Canada” (which used to be known as a “hard Brexit”) or “Australia” (which used to be known as “trading on WTO terms”, or, more succinctly, “no deal”). The most offensive new line insists that we will “restore our economic and political independence on 1 January 2021” – as though the UK is fighting the last battle to liberate itself from an invading empire, not voluntarily cutting itself off from the world’s largest trading bloc.

Perhaps ministers are softening people for the worst; perhaps they genuinely believe their own hype

The government’s campaign is not military but emotional, and not waged against the EU but the British people. The target and tactics are language itself.

Governments have long sanctioned and banned certain words and phrases from official parlance, and “message discipline” is not in itself a mark of extremism. And yet there is a difference between framing the narrative and reinventing it altogether. From the very beginning, Brexit has depended on distortion.

In 2016, leave campaigners used language both to terrify people and mollify them. Voters were promised “the exact same benefits” of EU membership at the same time as posters announced “Turkey (population 76 million) is joining the EU”. The most important slogan of all pledged that we would “take back control of our money, borders and laws”. It didn’t matter that we already had it. Campaigners tapped into a sense of both powerlessness and loss.

Boris Johnson understands the power of language astutely and instinctively. In 2016 he knew that people wanted to “take back control”, and in 2019 realised they finally wanted to “get Brexit done”. The slogans are designed to ring through people’s heads and convince them we are doing the right thing, even when the evidence to the contrary begins to mount. It doesn’t matter that Australia is negotiating a free trade deal with the EU and is in any case a relatively minor trade partner on the other side of the world: this friendly-sounding euphemism for “no deal” helps the government cover up what it has already done and obscures the reality of what it is about to do next.

Play Video 1:38 'There is no need for a free trade agreement': Boris Johnson outlines UK stance after Brexit – video

Johnson is in fact closer to Theresa May than he appears to realise. She, too, littered her premiership with calorie-free soundbites designed not simply to conceal but actively mislead. After months of “Brexit means Brexit”, she promised an “implementation period” with nothing to implement, and then “strong and stable government” in the face of mounting chaos. Perhaps the most shameless was a “global Britain” that would impose barriers on both foreign trade and foreign people. Even the word “Canada” was a clever piece of marketing, suggesting a progressive model for cooperation while actually necessitating a vast contraction to our economy and free trade. In the end, words came to signify their opposite meanings.

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Why does the government think it can get away with promising something sunny and open such as “Australia” when the reality will mean a self-imposed commercial blockade? Why does Dominic Raab deny there will be checks on the Irish border, when they will be experienced by businesses and people? Perhaps ministers are softening people for the worst; perhaps they genuinely believe their own hype.

The most accurate answer may, in fact, be the most troubling. If a government wishes to control the people’s attitudes, it must first control their lexicon. This is not simply an attempt to reframe voters’ opinions but their minds. The government seeks to confuse us with jargon, misinformation and contradictory statements, and deploys slogans to anaesthetise us from its actions. We eventually become so exhausted that we believe the government when it tells us to blame someone else, or else stop caring altogether. This, indeed, is taking control – but of the people, not for them.

A time traveller from the last century might not understand Brexit but would understand the government’s tactics clearly. Its language enacts George Orwell’s most chilling warning: that we reject the evidence of our eyes and ears.

• Jonathan Lis is deputy director of the thinktank British Influence