The government has been threatened with legal action by its own Covid inquiry – over a failure to provide it with key documents it says it needs to do its job.
Here’s what you need to know about the row:
What did the Covid Inquiry ask for?
The inquiry was announced by Boris Johnson in May 2021 to look into the UK’s handling of the pandemic. But it now wants more information about what the prime minister was saying in private at the time.
The Covid inquiry asked the government to provide "WhatsApp communications recorded on devices owned or used by" Boris Johnson, "comprising exchanges between senior government ministers, senior civil servants and their advisers during the pandemic".
These messages were to include both groupchats, and messages between individuals. The chats include discussions with chief medical officer for England, Sir Chris Whitty, the then chief scientific adviser, Sir Patrick Vallance, and the former NHS chief Simon Stevens.
It also asked for the ex prime minister's diaries for the same period, together with notebooks which "contain his contemporaneous notes". It has also asked for WhatsApp messages from Henry Cook, an advisor.
Why does the inquiry want them?
The inquiry says it needs the messages and notes because their contents will shed light on "core political and administrative decision-making by the UK government during the pandemic".
More generally, the inquiry wants to be sure that "all relevant contents of these documents are disclosed" – rather than leaving it to the government to decide which parts are relevant. Baroness Hallett, who is leading the inquiry, has also suggested that this approach is important to maintain public confidence.
The inquiry is also clear that it doesn't just want messages about Covid.
"It may be necessary for reasons of context for me to understand the other (superficially unrelated) political matters with which they were concerned at the time," the inquiry chair said - adding that it could show whether ministers were distracted by other matters.
What did the Cabinet Office do?
The government hasn't handed over the information in full. Instead, it provided extracts - which were redacted by the Cabinet Office legal team.
The Cabinet Office claims the redactions relate to “unambiguously irrelevant material”, and that the inquiry has no power to order its release.
But the government department did provide copies of "of a selection of materials, in unreacted form" so that the inquiry "could satisfy myself that the redactions that had previously been made to this particular set of materials were necessary on the basis that they covered information that was unambiguously irrelevant to the Inquiry’s work".
How did the inquiry respond?
The inquiry chair says this isn't good enough and that the government has "misunderstood the breadth of the investigation that I am undertaking".
It issued a legal notice ordering the documents be handed over.
"The key flaw, as it seems to me, is that it wrongly allocates to the holder of documents, rather than to the inquiry chair, the final decision on whether documents are or are not potentially relevant to the inquiry’s investigations," she wrote.
Baroness Hallett has extended the deadline for the Cabinet Office to provide the documents to 4pm on 30 May 2023.
What has Boris Johnson said?
Boris Johnson hasn't yet directly commented on this matter. But we know he has dropped his government-appointed lawyers which were representing him at the Covid inquiry.
Allies say he has lost confidence in the Cabinet Office because of a separate incident, in which the department passed information to the police that led to him being put under investigation for renewed Covid lockdown breaches.
The former prime minister's opinion may seem odd in the context of this episode, in which the Cabinet Office is apparently trying to hand over as little of his information to the inquiry as possible.
The opposition, meanwhile is making hay. Labour's deputy leader Angela Rayner said that "the fact the Covid Inquiry has had to invoke legal powers to compel the handover of crucial documents suggests that this is a government with much to hide".
"Rather than fighting legal battles to withhold evidence, it is essential that ministers now comply so the public is able to get to the truth and those responsible can be held to account," she added.
The government says it remains "committed to its obligations to the inquiry and in line with the law" but that it is "our position that the inquiry does not have the power to compel the government to disclose unambiguously irrelevant material".
