Visiting Watford, Boris Johnson made it commendably clear on Monday that he opposes the self-interested abuse of a process laid down by treaty and law. Asked about an American spy’s wife who has claimed diplomatic immunity after being involved in the death of a British motorcyclist, Mr Johnson could not, for once, have spoken more plainly. “I must answer you directly,” he said. “I do not think that it can be right to use the process of diplomatic immunity for this type of purpose.”

The remarks were welcome and to the point. But such rigour is rare coming from this prime minister’s mouth. The problem with Mr Johnson’s brief tenure of 10 Downing Street is the exact opposite of the point he made on Monday. He is not a consistent upholder of proper process at all. On the contrary, he is a shameless and serial abuser of it. This week, the damage being done to this country by this most untrustworthy of prime ministers is scattered as far as the eye can see.

Only two weeks ago, do not forget, Mr Johnson suffered probably the most humiliating constitutional reprimand ever inflicted on a British prime minister, when the supreme court unanimously dismissed his five-week prorogation of parliament as unlawful. The judges found that his move breached the principle that a government must be held to account by a sovereign parliament. The embarrassing implication was that Mr Johnson misled the Queen.

It is a mark of the unprecedented lack of trust which this prime minister now inspires that a Scottish court was asked on Monday to issue an order requiring him to uphold the law. In Edinburgh the court of session declined to issue such an order, which would have ensured compliance with the Benn act’s requirement for a Brexit extension if there is no new deal with the EU on 19 October. But it only did so on the basis that Mr Johnson’s lawyers had pledged in court that he would comply. Not to accept that pledge, the court said, “would be destructive of one of the core principles of constitutional propriety and of the mutual trust that is the bedrock of the relationship between the court and the crown”.

On his visit to Watford, the Conservative leader insisted again that Britain will leave the EU on 31 October. This will not be possible, under the Benn act, unless there is a deal in Brussels in under two weeks. That looks unlikely. Mr Johnson’s proposals for a deal fall well short of EU positions on multiple counts. President Macron wants everything sorted by Friday. Without an agreement, the Benn act comes into force, compelling Mr Johnson to do what he has always said he will not do. We shall see all too soon if the Scottish court was right to trust Mr Johnson.

The signs are not good. On Tuesday, the government plans to prorogue parliament until a Queen’s speech next Monday. It is true that the 2017-19 session is now the longest since the Long Parliament. But a Queen’s speech normally either follows an election or portends a new legislative programme.

This one is the opposite. It coincides with Mr Johnson’s plan to call an election and will thus contain nothing that will reach the statute book before the poll. In effect, as Professor Robert Hazell of the UCL Constitution Unit has argued powerfully, the speech is thus not a legislative programme but an election manifesto. “The Queen will have been used,” the professor says, “to make a Conservative party political broadcast.”

All this is entirely of a piece. Mr Johnson took office in July as head of a Tory faction. He has bulldozed precedent, propriety, parliament, his opponents and the country’s allies with Trumpian disdain. Most have fought back. They must go on doing so. Mr Johnson must be stopped from gaming with the Commons, the courts and the country. And, until a no-deal Brexit is off the table, he must be denied the general election he seeks.