An ugly legal spat between the Government and the official Covid Inquiry could see officials forced to hand over thousands of Boris Johnson's WhatsApp messages.
The Cabinet Office has until Thursday afternoon to submit the texts and a set of notepads the shamed ex-PM kept at the height of the pandemic or face possible legal action.
Baroness Heather Hallett, who is heading the probe into the UK's response to the Covid crisis, wants uncensored access to all messages sent by the ex-PM and several key players including Rishi Sunak.
But Downing Street has said most of the messages are "unambiguously irrelevant" to the inquiry.
And the waters were muddied further when the Cabinet Office said it doesn't actually have the WhatsApps or pads they're being asked for.
Rishi Sunak has declined to say whether the Government will give Baroness Hallett what she's asking for, opening the possibility that the Government could be taken to court by the probe it set up.
For his part Mr Johnson insists he's happy to provide all the info requested - prompting Downing Street to point out he's free to submit it himself.
Here we look at some of the key questions as the mess unfolds.
What's the inquiry actually asked for?
Baroness Hallett has set out the info she believes she needs in order to make a full assessment of the Government's response to the Covid crisis.
These include:
Lady Hallett has demanded a witness statement from a top civil servant accompanied by a statement of truth confirming they don't have the documents if the Cabinet Office fails to produce them by the new deadline.
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What's the legal situation?
All this was requested using section 21 of the Inquiries Act 2005 - making it a criminal offence not to comply.
But the Cabinet Office may challenge the order, setting up a court showdown between the inquiry chief and the Government.
Tonight, a spokesperson insisted the inquiry "does not have the power to request unambiguously irrelevant information that is beyond the scope of this investigation" such as personal WhatsApp messages.
A Cabinet Office spokesperson said: "We are fully committed to our obligations to the Covid-19 Inquiry. As such, the Cabinet Office alone has already provided upwards of 55,000 documents, 24 personal witness statements, eight corporate statements and extensive time and effort has gone into assisting the Inquiry fulsomely over the last 11 months.
“However, we are firmly of the view that the Inquiry does not have the power to request unambiguously irrelevant information that is beyond the scope of this investigation.
"This includes the Whatsapp messages of Government employees’ which are not about work but instead are entirely personal and relate to their private lives.”
Ministers could go nuclear and order a judicial review into the inquiry's powers.
But it would look bad for the Government to be holding out on an independent probe into its Covid response.
How can the Government decide evidence is 'unambiguously irrelevant' if it hasn't got it?
This is the issue at the heart of the dispute.
Downing Street says it shouldn't be forced to hand over the full trove of messages as it insists a large chunk aren't about Covid and therefore aren't relevant.
But Baroness Hallett maintains that she should be the one to decide what's relevant and what isn't.
She said the Cabinet Office previously redacted messages relating to the enforcement of Covid regulations by the Metropolitan Police during protests over the murder of Sarah Everard.
In a scathing response, Baroness Hallett said this was "not a promising start".
She may also argue that messages on other topics will highlight how focused Mr Johnson was on Covid with everything else in his inbox.
Ex-No10 aide Dominic Cummings - who has become his old boss's biggest critic - previously claimed to MPs that Mr Johnson was distracted from the Covid crisis by a story about the couple's dog Dilyn.
Mr Johnson's then-fiancée was allegedly “going completely crackers” on March 12 2020 about a report in the Times that the couple wanted to rehome their dog - something she described as "total crap".
Mr Cummings claimed she asked the press office to deal with the story as officials scrambled to deal with the escalating Covid-19 crisis and held meetings about potential military action in the Middle East.
The tricky part is that not all messages are routinely stored - so it begs the question of who decides what's relevant and what's not.
No10 says it's not read through everything and that final decisions will be made by legal advisors.
Could Boris Johnson just hand over the messages and pads himself?
Well, yes.
A spokesman for the former Prime Minister - who quit last summer after a series of scandals - said Mr Johnson would welcome the scrunity.
He said: "Mr Johnson has no objection to disclosing material to the inquiry. He has done so and will continue to do so.
"The decision to challenge the inquiry's position on redactions is for the Cabinet Office."
Downing Street has suggested there is nothing to stop Mr Johnson handing his personal evidence directly to the inquiry.
The Prime Minister's official spokesman said: "It is down to individuals to decide what personal information they are able to hand over, but there is a process for the Government-owned material.
"There's a distinction between Government-owned material, that would need to be disclosed by the Government, if it was their own personal information, then obviously they are able to make a judgment."
So, the ball's in your court Mr Johnson.
Where are the pads and the messages now?
This isn't entirely clear.
This morning the Covid Inquiry said it had been told that the Cabinet Office doesn't have them.
The Mirror has contacted Mr Johnson's team to find out if he has them stashed away for safekeeping.
Mr Johnson's team says the notebooks and WhatsApp messages have been handed to the Cabinet Office legal team, but he has since parted ways with his government-appointed lawyers.
Labour says the evidence that has seemingly "gone missing" must be found and presented to avoid the "whiff of a cover-up".
Deputy leader Angela Rayner said: "The fact the Covid inquiry has invoked legal powers to compel the handover of crucial documents in the face of legal battles and delaying tactics shows this is a Government with much to hide.
"It now appears that vital evidence has gone missing. It must be found and handed over as requested if the whiff of a cover-up is to be avoided and bereaved families are to get the answers they deserve."
Has Rishi Sunak handed over his messages?
Baroness Hallett has asked for messages to and from the then-Chancellor who's currently in the top job.
Mr Sunak, let's not forget, was a key player in the crisis, so for the probe to be effective it'll be crucial to see what input he was having.
He was, after all, behind both the furlough scheme and the controversial eat-out-to-help-out initiative which kept businesses afloat but is thought have led to the spread of infections.
Whether that's all been provided is unclear.
The PM's official spokesman said that thousands of documents and messages have been handed over to the inquiry, but said it would be "inappropriate" to discuss individual pieces of evidence.
Are ministers trying to cover up their messages to avoid embarrassment?
Cynics might well think so. And it's a view held by Lord Kerslake, a former head of the civil service.
He said: "There's some cover-up going on here to save embarrassment of ministers. But there's also the Cabinet Office fighting for a principle of confidentiality.
"I have to say I think they're misguided on this situation. I actually think it would set a helpful precedent if Lady Hallett prevailed in this fight about the information.
"We are in a bit of a mess at the moment, we don't really know whether WhatsApp's been used as a decision-making tool or, indeed, as just an information-sharing device."
Asked whether this was a fair assessment, the PM's official spokesman responded simply: "No."
Do messages by ministers not routinely get saved then?
Yes but no is the tricky answer to this one.
Downing Street has said there is no requirement to retain every WhatsApp message.
The Prime Minister's official spokesman said: "We do not permanently store or record every WhatsApp.
"The substantive and relative content, including decision making, is copied across to the official record in appropriate format for preservation.
"We wouldn't, as is standard, retain irrelevant material. There's no requirement to record every single communication for the public record."
How did this result in Boris Johnson being reported to police AGAIN?
One unexpected impact of this whole process is that Mr Johnson was once again reported to police over lockdown gatherings.
Over the course of its review of documents, Cabinet Office ministers spotted entries into his ministerial diaries which raised questions.
The Met and Thames Valley Police are looking into alleged breaches at Chequers, the PM's grace-and-favour home in Buckinghamshire.
But Mr Johnson's team were dismissive, branding the whole thing a "politically motivated stitch-up".
Thames Valley Police confirmed it had "received a report of potential breaches of the Health Protection Regulations between June 2020 and May 2021 at Chequers, Buckinghamshire".
Civil service rules meant staff were required to report the matter to police, the Cabinet Office said.
Will Rishi Sunak speak to Boris Johnson to iron this whole thing out?
That might sound like the easiest solution, but it doesn't look like it right now.
The pair are not scheduled to meet this week after suggestions they would hold clear-the-air talks amid a row over the Covid-19 inquiry.
It is understood there had been initial discussions about holding a telephone call but this is not scheduled to go ahead as it stands.
Is this a case of 'the dog ate my homework'?
The Lib Dems think so.
Deputy leader Daisy Cooper said: “This dog ate my homework type excuse from the government simply doesn’t stand up to scrutiny.
“For the Cabinet Office to simultaneously refuse to disclose Boris Johnson’s messages because they were irrelevant to the inquiry, whilst claiming not to even have them, will raise suspicions of another Conservative cover up.
"Rishi Sunak is too weak to stand up to Johnson and make him hand over this evidence, while bereaved families are being left aghast.
“The public has waited long enough already to get the truth. The inquiry’s work mustn’t be delayed any longer because of endless chaos in the Conservative Party.”
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