Why would ministers fight tooth and nail to prevent the release of Boris Johnson’s uncensored WhatsApps and diaries, and the correspondence of a relatively anonymous former political aide called Henry Cook? Rishi Sunak has little interest in protecting his No 10 predecessor and rival from any embarrassment. His relationship with Johnson remains almost as strained as when they were neighbours in Downing Street, and Sunak is now reluctant even to pick up the phone to Johnson for a rapprochement. Johnson has said he is willing for all his material to be sent to the inquiry uncensored, as has his former health secretary Matt Hancock. However, the Sunak administration’s battle to withhold the information is about far more than Johnson, despite the former prime minister’s domination of the headlines. In fact, this fight is entirely about the wider consequences for No 10 and the Conservatives if they agree to hand over unredacted information about the pandemic to Heather Hallett’s inquiry. This could mean all kinds of text messages, WhatsApps, emails, minutes, notes and diaries of numerous other ministers, aides and officials avoid the red pen of the government’s lawyers and ultimately make their way into the public domain. Sunak himself is the most prominent member of the government whose Covid-era material could end up having to be handed over unredacted. Other serving cabinet ministers who were around in the Johnson era include Oliver Dowden, the deputy prime minister; Suella Braverman, the home secretary; Michael Gove, the levelling up secretary; Thérèse Coffey, the environment secretary; and Grant Shapps, the energy secretary. Simon Case, the cabinet secretary – the UK’s most senior civil servant – was running No 10 at the time. The remaining unanswered questions about decision-making during the pandemic are endless. There is still little visibility around how lockdowns and restrictions were decided, who took the decisions, how closely the politicians listened to their scientific advisers and, importantly, whether Sunak ever believed that economic considerations trumped public health advice. Hancock’s correspondence, injudiciously handed to the journalist Isabel Oakeshott and then passed to the Telegraph, give us a flavour of the kind of casual communications that were common during the pandemic. That is a drop in the ocean compared with the wealth of material that Hallet’s inquiry is seeking. If the government backs down in relation to Johnson and Cook, it will have to take a similar approach to all this other material as well. And this is why many Whitehall observers believe the row is now likely to end up in a judicial review. There is a fundamental disagreement between the government and the inquiry’s “redaction protocol”, which makes clear it believes that its own lawyers – not those of the government legal department – should be in charge of what is deemed relevant. Some Tories and former civil servants, such as the former cabinet secretary Robin Butler, believe it may be possible to come to a compromise, with greater dialogue between the government and the inquiry over what redactions will be made. However, the gap between the inquiry’s position and the government’s seems extremely wide. In weighing up whether to seek a judicial review, Sunak will need to consider how it would look for his administration to try to conceal material from an inquiry that the government itself commissioned and a retired judge it appointed. There is a risk now for the prime minister that the whole process could lose credibility as a vehicle for establishing the truth about how the Covid pandemic was handled – even if he were to win on a point of law. Some former ministers involved in the pandemic response are frustrated at the lack of transparency and the implication that there is anything to conceal. No 10 will now have to decide what is a worse look for Sunak: a potential exposure of chaotic or incompetent decision-making during Johnson’s era, or a reluctance by his own administration to face up to the truth.