David Davis’s complaints about the EU are well-known, but on Tuesday we learnt of a surprising addition: its irritating habit of preparing for the consequences of Brexit. In a December letter to the prime minister, leaked to the Financial Times, the Brexit secretary complains that the EU is discriminating against the UK by warning stakeholders – including, according to the FT, drugmakers, seafarers and airlines – of the consequences of no deal, and apparently not giving enough consideration to more favourable outcomes.

Although every month feels like silly season when it comes to our EU withdrawal, this letter deserves to be singled out. For an uninitiated reader, its writer would appear to loathe Brexit. Davis expresses concern at the possibility of the UK being “treated differently by EU institutions” and of “agreements or contracts … being terminated in the event of a no-deal scenario”, and he declares with apparent outrage that “some EU agencies have published guidance to business outlining that the UK will become a third country when we stop being a member state”. Given that he is an avowed Brexiteer in a government determined to leave the bloc – which necessitates the UK’s future status as a third country without EU privileges – his complaints might potentially be directed closer to home.

It has been evident for many months that the government is bluffing, and is developing no substantive contingency plans

The letter is the latest blatant example of British cakeism. The government pretends that Brexit isn’t happening when the facts do not suit it; refuses to confront the realities staring it in the face; and reacts furiously when the EU declines to imitate its constructive ambiguity, failures of communication and outright delusion. Davis’s tone evokes the petulant indignation of a competitive but half-hearted amateur being shown up by dedicated and industrious professionals in the game he forced them to play.

On a political level, the missive demonstrates both the lack of goodwill between the UK and EU institutions, and our lack of influence. Specifically, Davis suggests that the UK has considered challenging the EU27 in court over the matter, which is arguably not conducive to cordiality and trust in the negotiating chamber. More significantly, he concedes that a case would stand little chance of success, and the government must therefore “increase our engagement with the commission”.

Davis’s attitude is revealing – and astounding. This is, after all, the man who has decreed our escape from the European court of justice an indelible red line, yet ponders recourse to it. But his suggestion of “engagement” is the most damning element of all. Knowingly or not, he exposes Britain’s vanishing influence. “Engaging” is in this case a euphemism for lobbying; it occurs when we no longer make our decisions and must depend on others to make them for us. For 45 years we have sat in a room with our most important political and economic partners, and occupied one of the prized seats; now all we can do is wait outside and beg to be heard.

Of course the crux of Davis’s protest is not Brexit itself, but the no-deal scenario. He deplores the EU’s consideration that the adventure might fail. His principal grievance in the letter, therefore, is that the EU is ignoring the prospect of an “implementation period or future relationship discussions”. Once again, he appears to resent that the EU might actively respond to a stated British government policy – namely the endlessly repeated mantra that “no deal is better than a bad deal”. In effect, Davis is complaining that the EU is taking him seriously, and acting on threats that he and the prime minister continue to make.

Quick Guide What are Brexit options now? Four scenarios Show Staying in the single market and customs union The UK could sign up to all the EU’s rules and regulations, staying in the single market – which provides free movement of goods, services and people – and the customs union, in which EU members agree tariffs on external states. Freedom of movement would continue and the UK would keep paying into the Brussels pot. We would continue to have unfettered access to EU trade, but the pledge to “take back control” of laws, borders and money would not have been fulfilled. This is an unlikely outcome and one that may be possible only by reversing the Brexit decision, after a second referendum or election. The Norway model Britain could follow Norway, which is in the single market, is subject to freedom of movement rules and pays a fee to Brussels – but is outside the customs union. That combination would tie Britain to EU regulations but allow it to sign trade deals of its own. A “Norway-minus” deal is more likely. That would see the UK leave the single market and customs union and end free movement of people. But Britain would align its rules and regulations with Brussels, hoping this would allow a greater degree of market access. The UK would still be subject to EU rules. The Canada deal A comprehensive trade deal like the one handed to Canada would help British traders, as it would lower or eliminate tariffs. But there would be little on offer for the UK services industry. It is a bad outcome for financial services. Such a deal would leave Britain free to diverge from EU rules and regulations but that in turn would lead to border checks and the rise of other “non-tariff barriers” to trade. It would leave Britain free to forge new trade deals with other nations. Many in Brussels see this as a likely outcome, based on Theresa May’s direction so far. No deal Britain leaves with no trade deal, meaning that all trade is governed by World Trade Organization rules. Tariffs would be high, queues at the border long and the Irish border issue severe. In the short term, British aircraft might be unable to fly to some European destinations. The UK would quickly need to establish bilateral agreements to deal with the consequences, but the country would be free to take whatever future direction it wishes. It may need to deregulate to attract international business – a very different future and a lot of disruption.

It has been evident for many months that the government is bluffing, and is developing no substantive contingency plans for the worst-case scenario. New lorry parks in Dover remain unbuilt, national replacements for EU agencies remain unassembled, and international certifications remain unsigned. The EU, on the other hand, correctly notes that no deal is not only an option, but in fact the default destination of the article 50 process. If nothing is agreed, the UK necessarily falls out of every EU treaty, body and law in March next year, with inevitably calamitous results. Voters may consequently ask why Davis finds the EU’s due diligence so offensive. Is he guilty of dereliction of duty in treating no deal with such nonchalance, or just dishonesty in claiming the government would ever enable it?

The fact that Davis is neither expecting nor preparing for no deal, and so deplores that the EU might be, demonstrates his awareness of the disaster. He might, also, secretly understand that there is little we could do in any case to mitigate the worst of the damage. But a no-deal scenario would only ever be at our insistence, not the EU’s. A government that prepares for self-immolation would do better to buy fire extinguishers than petrol.

David Davis’s letter shows that the government is addicted to its own mistakes. But the Brexit deal must, as things stand, be concluded in nine months. It is therefore time for the UK to show some honesty and maturity. We will not leave without a deal. We have almost no leverage in the negotiations. We will accept whatever Brussels offers us. And if the EU is taking Brexit seriously, so, perhaps, should the British government.

• Jonathan Lis is deputy director of the thinktank British Influence