Why does Rishi Sunak want to limit scope of Covid inquiry?

When Boris Johnson first announced a public inquiry into Covid, many observers saw it as an attempt to kick difficult questions into the long grass. Two years on, in a twist that may well amuse the former prime minister, that long grass is littered with political bear traps for Rishi Sunak.

Such are the complexities of this week’s developments, it can be easy to overlook the sheer strangeness of what is actually going on: a government going to the high court to try to limit the scope of an official inquiry it set up in the first place.

In May 2021, when Johnson announced plans for the inquiry – albeit one that would not begin for a year – he billed it as an opportunity “to get the answers that the people of this country deserve”.

Two prime ministers on, we are in the deeply curious position of Johnson, not a politician renowned for welcoming scrutiny, pledging to do whatever he can to give the inquiry all the information possible, while Sunak and his ministers launch a court battle to do the opposite.

The decision by the Cabinet Office to seek judicial review of the demand by the inquiry chair, the retired judge Heather Hallett, for full access to phone messages and other documents from Johnson has prompted condemnation from opposition parties and cries of betrayal from bereaved families’ groups.

The Cabinet Office reasoning, set out in a legal argument by Sir James Eadie, the barrister who in his role as first Treasury counsel advises ministers on the law, is that Lady Hallett’s demand for information goes far beyond what is relevant and also beyond the statutory scope of her inquiry.

“The compulsory powers conferred on inquiries by the 2005 [inquiries] act do not extend to the compulsion of material that is irrelevant to the work of an inquiry,” Eadie wrote.

Related: Boris Johnson hands over WhatsApp messages directly to Covid inquiry

Hallett vehemently disagrees and it will now be up to the high court to decide, a decision likely to take weeks even in the expedited hearing sought by the government.

Behind the legal case is a widespread assumption that Sunak and his advisers fear that handing over a trove of unedited documents from Johnson will set a precedent for the same thing to happen for the current PM and his ministers, with potentially embarrassing consequences.

Adding to the complexity is the fact that Johnson has made it plain he is very happy for the Cabinet Office, to which he handed his diaries and notebooks and WhatsApp messages, to pass these to Hallett in full – and that he will do so anyway.

In a particularly Johnsonian twist, he only has access to WhatsApp messages from May 2021 onwards as earlier ones are locked in a phone he was advised to never turn on again after the number was leaked.

Allies of the former PM insist he wants to help Hallett because he has nothing to hide, and feels a sense of duty to an inquiry he established. There is, nonetheless, a fairly evident sense of veiled glee at the difficulties this brings Sunak, whose resignation as chancellor heralded Johnson’s removal from No 10 last year.

“You have quite properly decided to leave no stone unturned in your search for the truth about government decision-making during the pandemic,” Johnson wrote to Hallett on Friday, a sentence seemingly calculated to raise the blood pressure inside Downing Street.

The political shenanigans have also highlighted the powers given to a statutory public inquiry such as Hallett’s, and the sheer scope of her investigations.

Among 217 pages of documents released by the Cabinet Office as part of its legal bid is a copy of the inquiry’s request for other evidence from Johnson, spanning 150 detailed questions.

These cover the logistics of the government’s response to Covid, and also the surrounding politics, including why Johnson failed to attend a string of early meetings of the Cobra emergency committee, and whether he considered sacking Matt Hancock as health secretary.

Others cover Johnson’s views on herd immunity, meetings with newspaper editors and, in one particularly striking question, whether he “suggested to senior civil servants and advisers that you be injected with Covid-19 on television to demonstrate to the public that it did not pose a threat”.

Similarly exhaustive requests are being sent to other ministers, aides and civil servants involved in the response.

One former government official said they had been reading old WhatsApp messages to prepare: “You can see these discussions happening under a premise that you now know was wrong, but you couldn’t have known at the time. It’s a bit like watching a horror film you’ve seen before, you’re like, ‘Oh, no, don’t go in that door.’”

The ubiquitous use of the messaging app was likely to aid Hallett, they argued: “People say government by WhatsApp is a bad thing, but you basically now have a verbatim record of all these conversations that would have previously happened on the phone.”

The official said they were phlegmatic about being asked to hand over every message, including personal ones: “I do think the inquiry will go through all this evidence and say: there was a lot of information people didn’t have, people basically did their best and there weren’t these humongous failures.

“But maybe I’ll be proved wrong. Maybe we’ll all end up with egg on our faces.”