Sir Keir Starmer’s Government is braced for further embarrassment as hundreds of documents covering Lord Peter Mandelson’s appointment and activities as ambassador to the US are expected to be published on Monday.
The massive release of files is the second relating to Sir Keir’s decision to give the prestigious Washington job to Lord Mandelson rather than a career diplomat.
Cabinet minister James Murray said there would be an “unprecedented” volume of information given to Parliament.
Officials have compared the scale of the effort examining documents related to Lord Mandelson to the sifting and disclosure of information to the UK Covid-19 Inquiry.
The release is thought to be the second largest publication to the House of Commons in history.
Health Secretary Mr Murray told Sky News: “I think the level of transparency is going to be unprecedented.
“The volume of information that’s going to be put out is unprecedented.
“It’s right we do that. We have been very clear that the appointment of Mandelson was wrong.
“Parliament then decided that this information will be made public. The Government is fully complying with that, and it’s important that we honour that commitment to transparency.”
MPs voted in February to demand ministers publish a wide range of documents relating to the appointment using an archaic parliamentary procedure known as a “humble address”.
The vote followed the launch of a police investigation into Lord Mandelson and concerns about the vetting process involved in his appointment.
A first tranche of documents, released in March, showed Sir Keir was warned of a “general reputational risk” because of Lord Mandelson’s connection to the late paedophile financier Jeffrey Epstein.
The second set of documents is expected to include messages between Lord Mandelson and ministers and Government advisers, including Sir Keir’s former chief of staff Morgan McSweeney.
Former health secretary Wes Streeting has already published his own messages with Lord Mandelson, including discussion over Gaza and criticisms of Sir Keir’s leadership.
But reports suggest it will not include Lord Mandelson’s UK Security Vetting (UKSV) summary after the Metropolitan Police asked the Government to withhold the document to avoid jeopardising its investigation into alleged misconduct in public office by the peer.
UKSV recommended against granting Lord Mandelson security clearance, but top Foreign Office official Sir Olly Robbins overruled that advice.
Sir Olly was effectively sacked in April after it emerged he had overruled the advice, with the Prime Minister insisting he was unaware of UKSV’s recommendation.
The Government has said it has only withheld documents where requested by the police, and all other documents will be published.
Several documents have also been redacted, either to remove personal details such as the names of junior officials, or on national security grounds.
Redactions on national security grounds were agreed with Parliament’s Intelligence and Security Committee following a compromise with MPs to head off a backbench rebellion on the demand for documents.
Last month, the committee raised concerns that the Government was applying redactions “too broadly”, and cited the UKSV vetting file as an example of documents being withheld without Parliament granting ministers the “authority” to do so.
The Conservatives have accused the Government of seeking to perpetrate a “cover-up”, with shadow minister Alex Burghart writing to the chief secretary to the Prime Minister on Sunday to demand “full transparency”.
Mr Burghart said: “I will remind you that the House did not provide the Government with the choice about redactions beyond the narrow scope in the humble address.
“This behaviour will be viewed by the House as a contempt of Parliament, and as a cover-up by the British public.
“Even if the Prime Minister leaves office in a few weeks, I can assure you we will hold you to account for this.”
A Government spokesperson said: “We are committed to complying with the humble address in full.
“The second tranche of documents will be among the largest publications ever laid in Parliament.
“That reflects the transparent and thorough process we have followed, in line with established precedent for humble addresses.”
