Ministers tell us privately they expect Rishi Sunak's deputy, Dominic Raab, to be the next senior figure to be shown the door by the prime minister.

But there is also a growing focus on what the prime minister knew when he appointed Mr Raab as his deputy.

Downing Street has repeatedly said Mr Sunak was not aware of formal complaints. There is no denial that informal issues were raised.

We've been told by well-placed sources that it was an open secret that there were concerns about Mr Raab's conduct.

One figure, familiar with the situation in a department in which Mr Raab worked, said simply: "Everyone knew".

A minister added: "Everyone in Westminster, I mean everyone, has known about this for ages. It's no secret. And anyone who says they haven't has chosen not to listen."

This person concluded: "He should have gone ages ago."

A former cabinet minister told us there was a palpable sense of dread in one department when Mr Raab took over under a previous administration.

It raises the question of how much Mr Sunak ought to have known at the point he appointed Mr Raab last October.

The prime minister has always insisted, as he did here under repeated questioning in a BBC interview in November, that he didn't know of any "formal" complaints about Mr Raab when he appointed him his deputy.

Following the BBC interview, a series of formal complaints were made, after Mr Sunak publicly encouraged them to be, and the inquiry by the KC Adam Tolley was set up.

Mr Raab is now the subject of eight formal complaints. The trade union the First Division Association, which represents civil servants, has said it understands dozens of people are involved in those complaints.

These span several years and a number of government departments.

Team Raab says he wants to make his case and will see this process through, playing down suggestions he might fall on his sword.

But there's a second problem for Mr Sunak and Mr Raab: The extent of the complaints which have been made.

One serving minister told the BBC the prime minister will find it hard to keep Mr Raab in his job, when an inquiry into his behaviour reports.

The minister said it was hard to ignore the number of people who had complained about the deputy prime minister's conduct.

The inquiry, which is speaking to witnesses right now, means people, including those with the strongest views and most arresting personal experiences of working with Mr Raab, are very reluctant to talk publicly about it.

But we wanted to share with you what people who have worked for Mr Raab, serve alongside him in government and in the Conservative Party are saying to us privately.

And explore why it is that the prime minister appears to have a persistent human resources problem: A party chairman sacked, a loyal supporter in Sir Gavin Williamson, a former minister, resigning over bullying allegations he said he refuted, and now this.

'It's going to be massive'

Mr Raab has told the BBC he is confident he has "behaved professionally throughout" but made "no apologies for having high standards".

His allies insist he is "cracking on with the day job".

Mr Raab was the most loyal ally during Mr Sunak's first - and doomed - attempt to become prime minister.

Was Mr Sunak blinded by a desire to repay Mr Raab's loyalty? Or is it right that he puts real weight on formal complaints, rather than the ever vibrant currency of Westminster gossip?

The simple truth is that after a few weeks of Nadhim Zahawi's fate being the government's oxygen snatcher, the fate of Mr Raab has now taken its place.

And that is prompting irritation.

"There isn't much sympathy for him, but due process must be followed," a senior minister says.

That due process is likely to last a few more weeks yet.

"I've never seen this side to his personality. He's always been courteous to me," another minister reflects before adding "while I am surprised by it, it clearly can't be ignored, given the alleged scale of it."

'The next Me Too'

Many are also privately pondering how different this investigation is compared to the one into Mr Zahawi, which took less than a week.

That was about establishing a paper trail, or the lack of one, about how much, or little, he'd told various bosses about his tax affairs.

The inquiry into Mr Raab rests much more on how behaviour is perceived.

One figure who would like to see the back of Mr Raab fears it is a big leap from someone who might be difficult to work with to bullying.

Others are more confident.

"Bullying is going to be the next Me Too," one Conservative MP says, in reference to the widespread and worldwide revelations of sexual harassment in recent years.

"It's going to be massive. And all this has such an inevitability about it."