A second batch of papers relating to Lord Mandelson's time as UK ambassador to the US was published on Monday.
It comes after MPs voted to release the documents in February, aiming to reveal behind-the scenes-discussions about how he was appointed to the role.
The peer was sacked from the job last year by Sir Keir Starmer following revelations in the United States about the extent of his relationship with the late convicted sex offender Jeffrey Epstein.
The document release totalled more than 1,500 pages. But some questions about the appointment remain unanswered.
The files contain more than 160 pages of messages and WhatsApps between Lord Mandelson and government ministers and officials.
But the disclosure did not include information from the peer's personal phone, after he declined a request from officials to hand it over.
We can see six messages between Lord Mandelson and Sir Keir in two brief exchanges, where they discuss campaigning in Bury in the run-up to the general election and praise former Conservative prime minister John Major.
On Tuesday, Downing Street confirmed the prime minister uses the disappearing messages function on his phone, and refused to say whether Sir Keir deleted messages that could have appeared in the documents published yesterday.
The PM's spokesman said the use of the function was permitted as long as it does not impact "record-keeping or transparency", and Sir Keir had handed over all relevant communications available to him.
We have not seen messages from Morgan McSweeney, Sir Keir Starmer's former chief of staff, who resigned following Lord Mandelson's sacking after mounting scrutiny over his role in pushing for the peer's appointment.
McSweeney reported his government phone had been stolen last year, and police say the device has not been recovered.
That means McSweeney has not been able to provide all his messages, although it is understood he has provided some of his messages to Lord Mandelson to the Cabinet Office, possibly from his personal phone.
Cabinet Office Minister Nick Thomas-Symonds has also said his personal phone was stolen last year. He says the device would have also contained messages with the peer. An ally has said he has shared details of the messages he could recall.
Some messages published by the government have been redacted for reasons of national security, or to protect the UK's diplomatic relations, so we don't know what those messages say.
The government has said Lord Mandelson was granted security clearance for the role by the Foreign Office, against the recommendation of United Kingdom Security Vetting (UKSV), which vetted him for the role.
Downing Street has said neither the prime minister nor any other government minister was aware of this at the time.
We had already seen a blank template version of UKSV's vetting form, published by the Cabinet Office, showing three tick boxes - green, amber and red - where officials can record their view on whether clearance should be given.
But the second batch of documents published on Thursday did not contain a copy of Lord Mandelson's vetting form.
Nor did it contain a document summarising his vetting, which is understood to be nine pages long.
A first tranche of documents, published in March, included a blank template sent to Mandelson for him to make a declaration of interests, but we have not learned any further details in these second set of papers.
The completed declaration of interest form, including details on conflict of interests and any action agreed to address any conflicts, also does not appear.
Sir Keir Starmer has previously accused Lord Mandelson of not fully disclosing the extent of his relationship with Epstein before he was appointed to the role.
We already knew that during due diligence checks prior to the appointment, McSweeney asked the peer three follow-up questions about his relationship with the late financier.
However, his answers to these questions have not been disclosed in the release published on Thursday.
According to McSweeney, these documents are among material held back at the request of the Metropolitan Police, who are investigating the peer over allegations of misconduct in public office. Lord Mandelson has denied wrongdoing.
The BBC understands Mandelson's view is that he answered questions about his relationship with Epstein in the vetting process accurately.
In messages between Lord Mandelson and then-chief of communications at No 10, Lord Matthew Doyle, the former ambassador raised concerns about the UK's deal to hand over the Chagos Islands to Mauritius.
The agreement would have seen the UK cede sovereignty of the territory to Mauritius and pay an average of £101m ($136m) per year to lease back a joint UK-US military base on the archipelago's largest island, Diego Garcia.
The deal, signed last year, has now been shelved by the UK after the US failed to formally confirm its approval earlier this year.
Back on 18 January 2025, two days before President Trump's inauguration ceremony, Lord Mandelson discussed US-UK relations with Lord Doyle, according to the documents published on Thursday.
Midway through a conversation about claims Lord Mandelson could be rejected by Trump due to his ties to the EU, the peer said: "I am getting very worried about Chagos".
However the next five messages are redacted, before the conversation picks up again about reports on UK-US relations.
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