A bitter clash has erupted after the Government threatened to switch off Boris Johnson's legal support funding if he "undermines" its position on the Covid Inquiry.
The former Prime Minister has caused a huge headache for Rishi Sunak after releasing his WhatsApps and notepads to Inquiry chief Baroness Heather Hallett.
This is despite the Government refusing to do so, instead launching a judicial review to prevent her getting hold of the documents.
Now it's reported that Mr Johnson's been told by Cabinet Office lawyers that legal support cash would "cease to be available" if he tries to tries to "frustrate or undermine" the Government's position.
Mr Johnson has been at the centre of a row as ministers launched a High Court bid to challenge the inquiry's demand for his unredacted WhatsApp messages and notebooks.
He said he was unwilling to be a "test case" for the Government's position, provoking massive anger in Whitehall.
The Sunday Times has detailed a letter sent by Cabinet Office lawyers to Mr Johnson last week.
"The funding offer will cease to be available to you if you knowingly seek to frustrate or undermine, either through your own actions or the actions of others, the Government's position in relation to the inquiry unless there is a clear and irreconcilable conflict of interest on a particular point at issue," it said.
They added that funding would "only remain available" if he complied with conditions such as sending the Cabinet Office "any witness statement or exhibit which you intend to provide to the inquiry so that it can be security checked by appropriate officials".
The Cabinet Office said the letter was "intended to protect public funds" so taxpayer-funded lawyers are not used for any other purpose than aiding the inquiry.
Former culture secretary Nadine Dorries, a staunch ally of Mr Johnson, said it was "not a good look for the Government".
"All evidence provided should be unfettered and not restricted by gov censorship - whatever form that may take," she tweeted.
Tory donor Lord Cruddas, an outspoken backer of Mr Johnson, who handed him a peerage, urged the MP not to be "held to ransom" by the threat.
"Don't worry @BorisJohnson I can easily get your legal fees funded by supporters and crowd funding, it's easy," he tweeted.
After the Government launched its legal battle, Mr Johnson wrote to the inquiry's chairwoman, Baroness Hallett, saying he was sending all the unredacted WhatsApps he had given to the Cabinet Office.
He said he would like to do the same for the messages on an old phone he was told not to use after it emerged the number had been available online for 15 years.
That device will be crucial, containing discussions before May 2021 including around the three national lockdowns he ordered.
Mr Johnson told the chairwoman that he was "not willing to let my material become a test case for others when I am perfectly content for the inquiry to see it".
The Cabinet Office missed Lady Hallett's deadline set on Thursday to hand over the requested material.
But the Government department has been trying to resist the publication of messages it believes are "unambiguously irrelevant".
A Cabinet Office spokesman said: "This letter from officials simply reiterates that taxpayer-funded lawyers must be used to aid the Covid inquiry and for no other purpose.
"The letter makes clear Mr Johnson has a duty to provide sincere witness to the inquiry independently and without reference to the views of the current Government.
"This letter was intended to protect public funds. It in no way prevents Mr Johnson from providing whatever evidence he wants to."
Rishi Sunak will also come under scrutiny during the inquiry into the response to the coronavirus pandemic, including potentially over his Eat Out to Help Out scheme to encourage diners back into restaurants back in August 2020 - months before the second national lockdown.
John Edmunds, the London School of Hygiene and Tropical Medicine professor who advised the Government on Covid-19 as part of the Sage committee, said the policy introduced by the Prime Minister when he was chancellor had not been discussed with scientists.
Prof Edmonds told the Observer: "If we had (been consulted), I would have been clear what I thought about it.
"As far as I am concerned, it was a spectacularly stupid idea and an obscene way to spend public money."
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