What did the second tranche of the Mandelson files reveal?

Today has brought with it the news that the Prime Minister does in fact use disappearing messages on his phone – after the Conservatives accused Sir Keir Starmer of not revealing his mobile communications with disgraced former US ambassador Peter Mandelson.

The second (and final) tranche of documents relating to Lord Mandelson’s appointment and time in office dropped on Monday afternoon.

It came after the Tories used a Humble Address motion in parliament to force its release, after Lord Mandelson was sacked from one of the most senior diplomatic roles in the country over his friendship with convicted paedophile Jeffrey Epstein.

Since then it emerged that Mandelson, while business secretary under Gordon Brown in the early 2000s, leaked market-sensitive information to the high-profile US financier.

The government said this week’s £1m data dump was an unprecedented show of transparency – yet there remain questions about the information that didn’t make it in. But what did – and is it significant?

Scottish Labour MPs were among those keen to flatter Peter Mandelson

More than 1,000 pages were released in the latest batch of files – and while they weren’t as damning as had been expected, a number of Labour MPs have been left a little embarrassed about the messages they sent to Peter Mandelson.

Ahead of the 2024 election, current Scotland secretary Douglas Alexander was in touch with the New Labour strategist frequently, admitting that ‘there’s very little enthusiasm for Labour, but a quiet determination to secure change’.

After Labour won a landslide that July, Alexander reached out to Mandelson again, writing: ‘Peter – thank you. (As usual) Your judgment was vindicated. You probably don’t realise quite how influential you’ve been in this whole improbable journey.’

In a subtle dig at former Labour prime minister Gordon Brown, Alexander thanked Mandelson for his ‘quiet and effective support when Gordon came out for [redacted] in the selection’.

When Peter Mandelson was made the UK’s ambassador to the US, Alexander jokingly dubbed him ‘the Comeback Kid!’. Then-Scotland secretary Ian Murray messaged the newly-appointed US ambassador in December 2024: ‘Congratulations your excellency.’

While warm exchanges are hardly uncommon between political colleagues, airing these conversations make things slightly more awkward for politicians hoping to put distance between themselves and the now-disgraced Labour peer.

Is Labour too tax-happy?

At the same time as Labour’s controversial welfare bill was making its way through parliament – it was eventually passed after a number of significant concessions were made – the Peter Mandelson files show Cabinet minister Pat McFadden, now the work and pensions secretary, confiding to the Labour peer that: ‘Every meeting I have is “who can we tax in order to pay benefits to others”. They’re asking the wrong questions.’

This was in response to Peter Mandelson asking whether the Prime Minister was aware of the discontent on the backbenches over his benefits bill: ‘The [parliamentary Labour party], I gather, is in [a] mutinous state.’

While Labour MPs in both government and on the backbenches privately agree with him, it hasn’t gone down swimmingly with the soft left of the party – many of whom protested the reforms, with some even rebelling against them at the time.

Disability benefits are devolved to Scotland but any cuts made to their UK equivalent would affect the block grant Holyrood receives – and potentially lead to Scotland making similar reforms. Given Pat McFadden is now running the Department for Work and Pensions, these unearthed comments have the potential to blow the argument on welfare open again.

Labour’s splits on energy go to the top

It wasn’t just welfare that Pat McFadden and Peter Mandelson converged on: the pair also discussed a public disagreement that emerged between former Labour prime minister Tony Blair and energy secretary Ed Miliband.

A policy paper from the Tony Blair Institute – which criticised the government’s net zero policies and stance on oil and gas – was published just days before tough council elections for Labour. Yet the files show that both Mandelson and McFadden sided with Blair over Miliband on the substance.

The energy secretary’s pushback on the report was described by Mandelson as ‘personal and stupid’, while Pat McFadden said that the ‘content’ of the analysis was ‘bang on’, but Tony Blair’s office got its timing wrong.

‘Odd mistake,’ Mandelson agreed, before adding: ‘I don’t think the government has clocked just how central energy supply and costs are to our economic future.’

The government’s position on energy policy is, of course, another point of contention within this current Labour group – and these remarks could further fuel discontent within the party.

Peter Mandelson was highly critical of the No 10 machine

‘They have highly sup-optimal personnel in No.10, SpAds [special advisers] and civil servants,’ Lord Mandelson complained in a WhatsApp message to Cabinet minister Pat McFadden in May 2025, as tensions about the welfare bill continued to rise in the Labour party.

The bill saw the biggest rebellion of Sir Keir Starmer’s premiership at that point. 49 of his Labour MPs voted against the bill at its second reading in the Commons (surpassing the rebellion Tony Blair faced in 1997 over his cuts to the lone parent premium), and though it passed, this was after significant changes had been made, and 47 Labour MPs still voted it down. Welfare remains a fiery issue for the Labour Party.

Discussing a conversation with the Prime Minister’s former chief of staff Morgan McSweeney, McFadden said in August 2025 – when Labour had dropped to 22% in the polls – that an idea about a new political strategy unit in No 10 was ‘a bit of a whirlwind’ and had ‘come from a lack of belief that good people will come into No. 10 and it’s hard to get the bad ones to leave’.

Mandelson replied: ‘I told [McSweeney] he needs an instrument/entity to recruit top people but I fear is using [this as an] excuse to keep people because he knows Keir won’t fire them.’

It doesn’t say much for those who have worked alongside the Prime Minister since his election nearly two years ago. At a time when Sir Keir Starmer’s future as Labour leader is in doubt, these revelations may provoke some serious reflection within Downing Street. Not that bringing Peter Mandelson into the fold in the first place has done them much good.