The prime minister or a successor must see the Northern Ireland Protocol Bill through into law

It can be said again and again that a prime minister is finished, but it is never so until he either resigns or is somehow forced from office.

However, Boris Johnson’s position is as perilous now as Theresa May’s just before she actually agreed a timeline for leaving office.

The political situations that those two prime ministers find/found themselves after three years or so in 10 Downing Street are in many respects quite different.

But it was hard to see how Mrs May could survive at the end, and it is hard to see how Mr Johnson does now.

The departure of Rishi Sunak and Sajid Javid, two key cabinet ministers, was clearly co-ordinated and is a devastating blow to Mr Johnson’s authority. It is akin to the resignation of Nigel Lawson as chancellor under Margaret Thatcher, and then of her other key cabinet minister Geoffrey Howe. Those two departures came roughly a year apart, and still finished her leadership.

They did not happen on the same day.

Mr Johnson shuns conventional rules of behaviour and niceties. He will try to brazen this out and might even do so for a few months. But it is telling that both Mr Sunak and Mr Javid criticised Mr Johnson’s populism, explicitly so in the case of Mr Sunak, who said that voters expect leaders to be blunt about difficult decisions and unpalatable choices that have to be made in the public interest.

It is, you might say, Mr Johnson’s tendency to tell people what they want to hear that helped lead us towards a disastrous Northern Ireland Protocol, which he then successfully denied existed (successfully because the PM got barely any heat for his Irish Sea border betrayal after it happened for more than a year).

Perhaps guilt is why he has tried to rectify it. Whatever the reason, it is an essential course.

And it is essential for balance in Northern Ireland that he, or any successor, see this NI Protocol legislation through into law.