Boris Johnson has long taken the view that rules have been created for others to obey and facts are flexible. When he was Brussels correspondent for the Daily Telegraph he was notorious for making up stories about how the European Union was conspiring to impose regulations on the shape of bananas or to ban prawn cocktail crisps. He had previously worked for The Times, until he was fired for allegedly fabricating a quotation from a family friend. He seems to have difficulty devoting enough time to get on top of the issues he is responsible for. Thus, his comment that the British-Iranian Nazanin Zaghari-Ratcliffe was “simply teaching people journalism” was not only untrue, but was cited in a court hearing in Teheran as “proof” that she was engaged in “propaganda against the regime”. As recently as this week, a British retailer, challenging Johnson’s claim that US trade policy prevented British manufacturers selling socks, said that “My opinion is that if it comes out of Boris Johnson’s mouth, it’s likely not to be true.”

Of course, given the sheer scale of issues that a prime minister must deal with, it is understandable that they sometimes struggle with detail. Thus, in his recent meeting in Luxembourg with Jean-Claude Juncker it has been widely reported that he expressed surprise when the complexity of trade across the Irish border was explained to him. He is not the only UK prime minister to lack an understanding of how the European Union works. Early in the Brexit process, Theresa May hosted a dinner in Downing Street with Juncker. It was soon clear that she had very little understanding of the complexity of the subject, seeming to think that the key elements might be resolved that evening. At one point he resorted to producing the 2000 page Croatian accession agreement to illustrate the scale of the challenge and, in a later call with Angela Merkel, said that  May was “on a different galaxy”. In her case there may have been an excuse. Before becoming prime minister most of her dealings with the EU had been on justice and home affairs. Prior to the Lisbon Treaty this was in what was termed the Third Pillar. In it, issues were addressed largely by the member states in the European Council, with little involvement of the other EU institutions, in particular the Parliament, Commission, and Court of Justice. It also allowed for a range of opt-outs, used particularly by Denmark and the UK. Thus, to some extent, it did allow what has subsequently been termed “cherry picking”. This changed with the Lisbon Treaty and it was never the case with what had been in the First Pillar, especially the single market. There, the elements were indivisible. Free movement of goods, which the UK wants post-Brexit, is inseparable from free movement of people, which it rejects. 

We now also know, from his recently published memoirs, that David Cameron was similarly unclear about the EU. He describes his frustration with British government lawyers “determined to defend the purity of European law” in the face of his attempts to find ways of rewriting domestic law to escape from its sway. He was clearly unaware of the fact that, at least in areas where the EU has competence, European law has to be supreme. How could you run a rules based organisation if every member made up their own rules?

Some will, of course, forgive our political leaders for their ignorance of the EU. After all, it is shared by many journalists and political commentators in the UK. Claims that the UK could rely on GATT Article XXIV or the Vienna Convention post-Brexit frequently go unchallenged, even though they are nonsense. Sweeping statements are made about how much will go on as before even with a no deal Brexit, oblivious to the absence of a continuing legal basis. All these things are important. The government’s attempts to reassure the public that the risks of no deal, such as disruption of supplies of medicines and food, can be mitigated are critically dependent on a legal certainty that ministers have consistently been unable to specify. 

One would hope that British politicians understand how the system of government in their own country works. Sadly, it seems not.

In a remarkable unanimous decision, the UK Supreme Court has ruled that the decision by the prime minister to prorogue Parliament for five weeks “was unlawful because it had the effect of frustrating or preventing the ability of Parliament to carry out its constitutional functions without reasonable justification”. It proceeded to rule that the Order in Council, given by the Queen, was “unlawful, void and of no effect and should be quashed”. 

But did the prime minister know that what he was doing was likely to be ruled unlawful? That may never be known. Former cabinet minister Amber Rudd has said that “Despite personal assurances from the PM, the Cabinet was not shown the legal advice around this prorogation”. This is the problem. Even if three successive prime ministers, as well as many others in the Westminster bubble, have failed to understand how the EU works, many others have. It is really not that difficult.

So maybe the problem is rather that the UK has a political class that is so arrogant that it sees no need to obey the rules, or even to learn what they are, because, in so many other areas of their lives, those rules have not applied to them. If this is really so, then it suggests that the process of negotiating a future relationship with the EU, which can only begin after some sort of withdrawal agreement on money, citizens’ rights, and the Irish border has been concluded, will be long, difficult, and characterised by continued misunderstanding. 

Martin McKee is professor of European public health at the London School of Hygiene and Tropical Medicine.