Gradually, then all at once. Attributed to a quote in a Hemmingway novel about how someone went bankrupt, it has been predicted by many that that is how Boris Johnson's leadership would end.

Johnson had seemed impregnable nearly three years ago when he won an 80 seat majority and seemed to deliver on his electoral mandate to get Brexit done.

Then there was his seemingly successful handling of the Covid pandemic.

However, it was his long observed problem about sticking to the truth that came back to haunt him.

When he was caught out in a series of evasions and disingenuous statements about his knowledge of previous allegations against deputy whip Chris Pincher, he resorted to saying he had forgotten about a previous case.

Very few if anyone believed him.

Many of his own party ran out of patience.

As former Health Secretary Sajid Javid said "enough is enough". They were not willing to give him the benefit of the doubt anymore.

The resignations became a cascade and then the end came quickly despite Johnson's attempt to again deny the political gravity of the situation.

Before that it had been a 'drip, drip' effect with Johnson under regular pressure over a number of issues.

His promise in the last election to build 40 new hospitals was queried at the time and again recently. The number is a lot less than 40 and they are not all new buildings.

He promised to get Brexit done and said the Northern Ireland Protocol was part of an "oven ready deal" and that there would be no customs checks between Great Britain and Northern Ireland. That was not true and his response to difficulties has been to simply ignore the international treaty he signed.

And he was praised for his handling of the Covid pandemic, but of course it turned out lockdown parties were being held in No 10 despite his denials to parliament.

There was another key turning point, in what has been described as a 'Trump-style standoff' or even 'Berlin bunker' last hours and that was the sacking of Housing Secretary Michael Gove.

A No 10 briefing later described Mr Gove as a "snake". That was based on the belief that Mr Gove had told the media he had told Boris Johnson to go.

Apparently that caused outrage in the Conservative party and questions about Mr Johnson's fitness for office.

Boris Johnson and Michael Gove had been friends and known each other since university. They fell out in 2016 when Gove entered the Conservative leadership race scuppering Johnson's chances.

Gove had been Johnson's campaign manager for the race and it was considered an act of betrayal. The other side of the argument was that Johnson was making a mess of the campaign and Gove ran out of patience with him

At the time Gove paid tribute to Johnson as a person, but said he did not think he had the qualities to be a prime minister.

That seems prophetic now and it's a sentiment that has been repeated by his former allies in recent days.