Here is Pippa Crerar and Henry Dyer’s explainer about what will be in the Mandelson files.

Good morning. Many people despair at the quality of governance in Britain at the moment, but in one respect we are living through a golden age; if you are interested in contemporary history, and learning about what actually happens at the heart of government, then you can now – sometimes – access the sort of information never available before.

Today the government is publishing a mass of information – apparently running to three volumes, and more than 1,000 pages – containing the private messages Peter Mandelson exchanged with government ministers and officials when he was ambassador to the US, and before his appointment. Last month a minister compared this to the evidence released as part of the Chilcot inquiry into the Iraq war. But the Chilcot inquiry took place in the era before WhatsApp, and it was publishing secret memos – intended for circulation within Whitehall. WhatsApp messages are a lot more personal; reading them is like being able to eavesdrop on a private conversation. Mandelson is a man with spiky, controversial views, who loves gossip and plotting, and whose private views don’t always accord with what he has said in public. It should be fascinating.

These documents are being published because the government has to comply with a humble address – a Commons vote mandating ministers to release information – tabled by the Conservative party. Several humble addresses have been passed in recent years (since this ancient parliamentary mechanism, which had been forgotten about for decades, was revived during the Brexit wars by the Labour Brexit spokesperson, a certain Keir Starmer) but none of them have been as far-reaching as this one.

The Conservatives tabled the humble address because they wanted to learn more about how Mandelson came to be appointed ambassador to the US despite the fact that it was known at the time that he had maintained a friendship with Jeffrey Epstein even after he was first convicted for child sex offences. As Kiran Stacey, Henry Dyer and Pippa Crerar report, the documents out today will imply that the Foreign Office did not seem particulary bothered about ensuring that the supposed “mitigations” in place to manage the risks associated with Mandelson being appointed amounted to very much.

But, on the broader question of why Mandelson was appointed, we are unlikely to learn much because it is already obvious why he got the job: he wanted it, he was close to Morgan McSweeney, the PM’s chief of staff who had more influence over what Starmer did than anyone else, and McSweeney and Starmer were both persuaded that Mandelson’s fondness for dodgy billionaires would enable him to form a good relationship with Donald Trump (even though this argument was inherently flawed, because the Trump administration did not want him).

Instead, the main revelations this afternoon are likely to focus on what members of the government have been saying about each other in private. On the Today programme Chris Mason, the BBC’s political editor, said some of the messages would be “excruciating”. Financial Times says: “The messages are expected to include frontbenchers and Mandelson trading humiliating remarks about Starmer.” Politico’s London Playbook says: “One person familiar with the content of the files told Playbook it will be ‘toe-curling’.”

Government sources have been saying they don’t expect any of the revelations to lead to resignations. That’s not much of a bonus; for the Conservative party, today will probably feel like Christmas has come early.

Ironically, one person not likely to be embarrassed about any of this is Trump. Government ministers are always diplomatic and polite about the US president in public. It is fair to assume that, in private, their views are a bit more aligned with the views of normal people, like you and me. But parliament agreed that material deemed “prejudicial to UK national security or international relations” would be withheld, so any juicy anti-Trump stuff will remain secret.

James Murray, the new health secretary, has been giving interviews this morning. Speaking about the release of the Mandelson files, he 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.

Here is the agenda for the day.

11.30am: Downing Street holds a lobby briefing.

2.30pm: John Healey, the defence secretary, takes questions in the Commons.

Afternoon: The government is publishing the rest of the Mandelson files. Darren Jones, the chief seceretary to the PM, will make a statement to MPs to mark their publication after 3.30pm. The documents should be published when he gives his statement at the latest, but may come a bit earlier.

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