There are plenty of beneficiaries of Priti Patel’s slow-motion fall into the political abyss. The opposition, obviously, which gets to look on as the British government crumbles before its eyes. On her own side, there will be ambitious colleagues glad to see a rival cut down. The most ardent remainers might feel a special gladness at seeing a Brexiteer humbled. But none of them will have gained as much from Patel’s woes as the foreign secretary, Boris Johnson.

Let’s start with the international development secretary herself. As she boarded her return flight from Africa, cutting short a trip that had barely begun, the case against her seemed clear and conclusive. In August she had held a dozen unauthorised meetings in one of the most politically sensitive regions in the world: Israel. Those included an encounter with the prime minister Benjamin Netanyahu. She had given misleading and incomplete statements about the trip. Even when pressed to give a full account of her contacts with Israeli officials, she had failed to mention two further meetings held after her supposed holiday. And, we learned today, she had visited the Golan Heights accompanied by Israeli officials, in violation of UK government policy towards a territory whose annexation by Israel the UK does not recognise.

There would be several grounds here for dismissal. It could be the trip itself or the apparent attempts to cover it up. Many had singled out Patel’s failure to notify Downing Street, which had seemingly left Theresa May badly exposed when she met Netanyahu in London last week, the PM blissfully unaware that one of her ministers had had earlier contacts with the Israeli leader.

But the picture became a lot murkier today. According to the Jewish Chronicle, May was not entirely in the dark after all: the PM and Patel had a conversation in September about the latter’s meeting with Netanyahu. The JC goes further, suggesting it was Downing Street that urged Patel not to come clean about one of the later meetings she had had with a senior Israeli official. Downing Street denies that account, but it would leave the case for Patel’s dismissal resting on the second of those later meetings: a 7 September session with Israeli security minister Gilad Erdan at the House of Commons. No 10 only learned of that one yesterday.

The irony here is that Patel could have avoided all this trouble if she’d simply followed normal diplomatic protocol, disclosing all her meetings, accompanied only by departmental officials. No one could have objected too loudly to a development secretary meeting ministers or NGOs in a foreign country. Even her most controversial proposal – headlined as sending UK aid to the Israeli army – could have been explained. She wanted the money to go to a field hospital the Israeli military has established in the Golan Heights and which is treating wounded Syrian civilians and rebel fighters. That might not be smart policy, especially given UK non-recognition of Israeli sovereignty over the Golan Heights, but it’s not obviously the stuff of scandal. In this case, as so often, it’s not the deed itself, but the cover-up.

Quick Guide Boris Johnson's errors of judgment Show Nazanin Zaghari-Ratcliffe Boris Johnson said that the British-Iranian citizen Nazanin Zaghari-Ratcliffe, convicted of spying in Iran, was “simply teaching people journalism” – a statement her family and her employer both said was untrue. His comments were subsequently cited as proof that she was engaged in “propaganda against the regime”. 'Dead bodies' After Johnson suggested that the Libyan city of Sirte might become a new Dubai once “the dead bodies” were removed, Downing Street said it was not “an appropriate choice of words”. Myanmar The foreign secretary was accused of “incredible insensitivity” after it emerged he recited part of a colonial-era Rudyard Kipling poem in front of local dignitaries while on an official visit to Myanmar. Whisky sour Johnson apologised after causing a “livid” reaction in a worshipper in a Sikh temple in Bristol by discussing his enthusiasm for ending tariffs on whisky traded between the UK and India. Alcohol is forbidden under some Sikh teachings. Continental drift Boris Johnson referred to Africa as “that country” in his Conservative party conference speech.

Tweet like Trump The foreign secretary suggested he wished he could tweet like Donald Trump, despite intense criticism of the US president’s use of Twitter, on which he has launched personal attacks against his foes.

The gradual drip-drip of revelations has kept the Patel story on the front pages for days. Which brings us to Boris Johnson. Were it not for Patel, the dominant scandal of the week would be the foreign secretary’s testimony that Nazanin Zaghari-Ratcliffe, a dual UK-Iranian citizen, now jailed in Iran, had been engaged in “teaching people journalism” in that country – a claim that contradicts and undermines the insistence of her employer and family that she was simply on holiday. With a casual aside, Johnson has risked a UK citizen spending an extra five years in an Iranian jail.

Conservative backbencher Anna Soubry is right: Johnson “has proved himself lacking in the qualities needed in a foreign secretary” and should be sacked. He is meant to be the country’s chief diplomat, in command of his brief, including its detail. Yet Johnson continues to think his cheery bluster, his shtick, exempts him from that obligation. But it doesn’t. In his job, detail matters: as the wartime posters put it, loose talk costs lives.

The Financial Times reckons Johnson might “be the least distinguished figure to occupy the Foreign Office” since 1945. That verdict is damning, but deserved. Patel’s behaviour was egregious, but it’s Johnson’s that has exacted the greater human cost - even if, thanks to Patel, it has got less attention. The very least we should expect is that he be fired. That he is likely to survive only confirms the paralysis of a prime minister heading a government decaying by the day.

• Jonathan Freedland is a Guardian columnist