Mandelson saga is a messy palaver - and the questions continue to swirl

And a few weeks after that, Lord Mandelson failed his developed vetting.

Sir Olly, just weeks into the job, learnt this knowing that Lord Mandelson had already been appointed.

The prime minister wanted to send this Labour grandee to Washington. Imagine the brouhaha if the appointment had been unannounced, if he had had the job taken from him before he even started.

And all this was going on at just the point that Donald Trump was about to begin his second term in the White House – the very reason Lord Mandelson was given the job in the first place, as he was seen as the political savvy, charming, wily consigliere who could win over the White House.

In other words, he was the unconventional ambassadorial appointment to deal with the unconventional presidential victor.

Getting a job, and it being publicly announced, before the vetting process is complete is unusual, I'm told. And yet it happened in this instance despite the high profile nature of the job and the high profile and colourful nature of the person who had got it.

One person said to me the Foreign Office usually advises prospective future employees to avoid handing in their notice on their previous job until their vetting is signed off – because until it is, the job can't be guaranteed.

But that didn't happen in this case, such was the rush to get Lord Mandelson out to Washington pronto.

So now we await the further tussle of the embattled knights, Sir Keir Starmer and Sir Olly Robbins, potentially one day after another in parliament in a few days time. Sir Keir will appear on Monday afternoon and there is an invitation for Sir Olly to do so on Tuesday, in front of the Foreign Affairs Select Committee.

One already elbowed out of a job; the other, the prime minister, who's done the elbowing, narrowly avoided the same fate at the hands of his own party in February.

And yes, it was this same wider row about Lord Mandelson swirling then too.

Supporters of the prime minister say the case made by Prof Martin, that Sir Olly was dutybound not to tell the prime minister, adds credibility to their insistence that Sir Keir only knew about all this earlier this week - and so has not lied.

They also say the Guardian's latest story, confirmed by the Cabinet Office, that two other senior civil servants knew about Lord Mandelson's vetting fail last month, are case studies in how the Whitehall machine should work – checks and due process followed by telling the prime minister – rather than other examples of No10 being kept in the dark.

But the Conservatives and others point to a story from the Independent's political editor David Maddox last September which claimed then that Lord Mandelson didn't clear security vetting.

Maddox even published his WhatsApp exchange with Downing Street in which he sought a reply from them.

Why, given this, were more questions not asked then?

The wider political question now is does all this curdle into lumps of rancour and grudge among Labour MPs imperilling Sir Keir Starmer again, with a big set of elections around Britain two weeks on Thursday?

Labour folk are considerably less than delighted - but also have campaigning to focus on - so let's keep an eye on what they're saying in the coming days, and weeks.