Cabinet Office may take legal action to deny Covid inquiry Boris Johnson material

Such a challenge over Lady Hallett's request for unredacted diaries and messages would be seen as unprecedented

The Cabinet Office could take unprecedented action to prevent Boris Johnson's unredacted diaries and WhatsApp messages being handed over to the official Covid inquiry, the Guardian had been told.

Officials are preparing to issue a response to the inquiry chair, Heather Hallett, by 4pm on Tuesday. Sources said they were likely to resist her demand for a cache of documents relating to the former prime minister's time in No 10.