More than 20 years ago, Boris Johnson was beginning to be famous. I was asked to appear in a documentary about him. He had recently been adopted for a parliamentary seat while editor of The Spectator, despite having indicated to the paper’s proprietor, Conrad Black, that he would not do this.

“How did Conrad Black feel about that?” asked the interviewer. In the funny way that sometimes happens when broadcasting, I could hear myself saying, “Well, I think he might have felt like David Niven, who said of Errol Flynn: ‘You knew where you were with Errol Flynn. He always let you down’.”

As soon as the words were out of my mouth, I felt I had been unfair to Boris and rang him to apologise. He was, not surprisingly, annoyed with me. It is not true that Boris always lets you down: he is capable of acts of great kindness. But I was not completely wrong either. The fairer way to put it would have been to say that Boris is reliably unreliable.

This is not a secret which has been uncovered by the recent revelations: it has been visible throughout his public career. It is undoubtedly a defect, but it is one which, in politics, has its uses (think of Disraeli, Lloyd George, Harold Wilson). It is very hard to trap him.

Is Boris Johnson – no longer a mere editor, but Prime Minister – now trapped? Many believe so, and many believe he ought to be. It is hard to justify his actions and inaction in relation to parties/ “gatherings”/ “work events” in Downing Street during Covid lockdowns and restrictions, or his reluctant and fragmentary accounts of what happened. I shall not try. He himself spoke on Wednesday of “the rage [millions of people] feel with me …when they think that … the rules are not being followed by the people who make the rules”. Many do feel that rage. Even the Queen is entitled to be one of them. I am not going to argue with them.

This does not automatically mean, however, that Boris should resign. Getting rid of a prime minister should be an act of the most careful, concerted policy. If it is merely an act of fury, it will have disastrous effects.

The electorate, of course, is entitled to throw out any governing party – and therefore the prime minister – for any reason, at a general election. But, without a general election, the only assassins are MPs of that governing party. There are few reasons, ever, good enough to justify the deed.

MPs should act only in very extreme circumstances – if a PM’s chief policy has failed (Chamberlain in 1940, Eden after Suez, Theresa May over Brexit), for example, or if he/she has lost an overall majority (Heath in February 1974, May in 2017). Even then (as in all the cases just mentioned), the fall is rarely immediate.

And when they act, the assassins must know what to do next. In 1990, there were good reasons to be fed up with Margaret Thatcher, but not good enough to meet the high threshold I have just described. Forcing out a leader who had won three overwhelming general election victories produced the bitterness and lack of direction that dogged the Conservative Party for the next quarter-century.

Many say, of course, that the current case is a very extreme circumstance. It is certainly a dreadful mess, giving a whole new meaning to the Leninist phrase about “the leading role of the party”. But I wonder, once the righteous anger had passed, how good it would feel for the country if the head of government had been ejected on this issue.

We may now be moving nearer to normality in relation to Covid-19. The Government, which was too draconian earlier on, now seems broadly on the right track, pushing back against scientists and social engineers in love with semi-permanent lockdown. Isn’t it better to stick to this course, without the self-indulgence of political convulsion? The international comparisons are quite favourable to Britain. We are not facing the collapse of the Government’s main policy. If anything, we are beginning to see its success.

Then there is the point that politics is, as the late, great political journalist of the moderate Left, Alan Watkins, loved to repeat, “a rough old trade”. In the age of Twitter, many MPs seem to think they are in Parliament because of their own sturdy independent-mindedness and bear no responsibility to the collective.

Actually, no. Almost all of them are there because of the party label they hold – the regiment, if you like, in which they have chosen to serve. They need to understand that the regiment will come under constant attack, and they cannot survive individually if they crumple under each bombardment.

To the above should be added those discontented for other reasons. I have a lot of sympathy with Dominic Cummings’s frustrations with Boris when he worked for him in Downing Street, but none with his attempt to prove him unfit for office by waging a continuous media campaign. 

If the two fell out, there will be fault on both sides, but the benefit of the doubt must go to the executive who is elected, not to the adviser who no longer advises.

For all Boris’s evident faults – so evident that Conservative MPs knew most of them when they chose him – his record of advancing his party is almost unspotted. Twice managing to become Mayor of London – a very unTory city – he then won the EU referendum, thus accumulating the electoral capital to lead his party when Mrs May failed. He won a commanding majority at the ensuing general election on the proposition that he would get Brexit done and crush Jeremy Corbyn’s Labour Party. The May era proved that no one else could do that.

I realise that gratitude is not a strong emotion in politics, and the polls are bad now, but Tory MPs should at least recognise that such skills are not easily replicated. The leading contenders if Boris falls – Rishi Sunak, Liz Truss and Michael Gove – are all able politicians, but none has exhibited anything like Boris’s reach. This man has come close to political death before – when Michael Gove denounced him after the referendum and when he failed as Foreign Secretary.

He has also come close to actual death – when he got Covid in the early days of the plague. But he has a way of surviving and reviving. These skills deserve respect from the party he leads. If they try to kick him out, they create a definite split for an indefinite benefit, possibly provoking the third general election in five years. Who needs that?

One must ask who stands to benefit from the blond defenestration being talked of. Lord Adonis, the Remainer whose frankness is so helpful to the other side, tweeted this week: “If Boris goes, Brexit goes.” That is the idea. That is the constant motivation of a minority of unreconciled Tory MPs and a majority of the Great and the Good in the Civil Service, academia, the law, the House of Lords and the BBC, which is carefully managing this current story for the political effect it has always wanted.

They must be thrilled that the mandarin Sue Gray has been granted by Boris power over his political life or death. The way she writes her report will be a real test of Civil Service impartiality.