The UK Covid-19 Inquiry could receive all of Boris Johnson’s unredacted WhatsApp messages and notebooks relating to the pandemic despite a Government legal challenge, a preliminary hearing has been told.

The Cabinet Office is bringing forward a judicial review of inquiry chairwoman Baroness Hallett’s request for all of the former prime minister’s WhatsApp correspondence and notes.

Ministers have confirmed that they expect an expedited High Court hearing to take place on or shortly after June 30.

But according to the counsel for the inquiry, Hugo Keith KC, the chairwoman is likely to be able to inspect much of the contested material before the case is heard due to the former Conservative Party leader offering to hand over the information directly and bypassing the Cabinet Office.

The concluding point is, we will shortly gain access to all the material on an unredacted basis

Mr Keith told Lady Hallett: “The concluding point is, we will shortly gain access to all the material on an unredacted basis.”

Tuesday’s preliminary hearing in central London heard that the inquiry’s legal team is seeking to inspect next week Mr Johnson’s WhatsApp messages dating from after May 2021.

“The inspection will allow your team to make its own assessment as to the redactions applied by the Cabinet Office and to satisfy ourselves and ultimately you of their appropriateness or otherwise,” he said.

It has also requested the Cabinet Office to return Mr Johnson’s notebooks to him by June 12 to start a similar inspection process so it can “compare them to the redacted copies already provided by the Cabinet Office”.

Mr Keith said the same inspection could potential be done with messages on a locked phone of Mr Johnson’s.

Mr Johnson changed phones in May 2021 after security concerns were raised that his mobile number had been publicly available online for 15 years.

He was advised to stop using the phone and not to access it again.

Mr Keith said: “Neither Mr Johnson nor the inquiry has the technical expertise to ensure the contents of the phone can be downloaded safely and properly, particularly bearing in mind the overarching need to ensure no damage is done to national security.

“We have therefore agreed that this phone should be provided to the appropriate personnel in government for its contents to be downloaded.

“We have asked the Cabinet Office, in liaison with Mr Johnson and those government personnel, to obtain the phone without delay, to confirm in writing the process by which it will be examined and to give confirmation that it, like the diaries and the notebooks and the WhatsApps, will be accessed fully.

“That is to say, there will be no redactions made to the contents, other than in relation to national security, before we may view it.”

Lady Hallett, in her first public remarks since the legal challenge was started, opened the session stating that she could make “no further comment” on the judicial review due to “pending” litigation.

The retired senior judge’s deadline for the UK Government to hand over the former prime minister’s unredacted material was missed by the Cabinet Office last week, with ministers instead announcing plans to challenge the request in the courts.

Ministers have defended the highly unusual move, citing concerns over material that is “unambiguously irrelevant”, despite doubts by some legal experts and ministers over whether they are likely to win the case.

Lawyers representing the Cabinet Office were due to address Lady Hallett on Tuesday.

The preliminary hearing is focusing on Module 2 of the inquiry, which will look into core political and administrative decision-making by the UK Government.

Preliminary hearings will consider how the investigation should be run rather than taking evidence, with the first public evidence to be given next week.