Today’s advocates of a windfall tax on the UK’s highly profitable banking sector detected a whiff of familiarity in Peter Mandelson’s suggestion, back in 2009, that JP Morgan should “mildly threaten” the chancellor.

Feeding a Wall Street financier market sensitive titbits was an extraordinary breach of trust – perhaps even illegal, it seems – but for Labour veterans of the financial crisis, Mandelson’s collusion with the banks against his own colleagues was the worst betrayal.

The then business secretary told Jeffrey Epstein by email that he was “trying hard” to change government policy on a bankers’ bonus tax; and appeared to recommend a fresh round of lobbying, suggesting the JP Morgan boss Jamie Dimon press the then chancellor, Alistair Darling.

The economic backdrop today is dramatically different from the depths of the banking crisis. But the clash between progressive policies and the powerful financial sector laid bare in the Epstein emails is still evident – and as in the case of Dimon, even some of the characters are the same.

Labour insiders from that time expressed outrage and disgust at Mandelson’s behaviour. One senior figure in Darling’s Treasury said the late chancellor would have been “shaking with rage” if he had known of Mandelson’s disloyalty.

“There was a lot of anger in the Treasury at the time about the bankers,” they recalled, underlining the fragile nature of the situation. Extraordinary sums of taxpayers’ money had been pumped into the ailing banks to prevent the complete collapse of the financial system.

Amid public fury about the role of bank bosses in driving the sector – and the British economy – to the brink of disaster while lining their own pockets, Darling had decided to slap a one-off 50% supertax on bonuses above £25,000.

Darling recalled in his book about the crisis that Dimon – whether or not prompted by Mandelson’s email to Epstein – rang him up, “very, very angry” about the plan.

“He said that his bank bought a lot of UK debt and he wondered if that was now such a good idea,” Darling recalled. “I pointed out that they bought our debt because it was a good business deal for them. He went on to say they were thinking of building a new office in London, but they had to reconsider that now.”

The apparent outburst made no difference to Darling’s position, and he continued to implement the bonus tax as planned.

More than 16 years on, and another Labour government, in a different era, opted not to risk alienating the titans of finance.

It was the self-same Dimon who issued an upbeat statement welcoming Rachel Reeves’s budget and announcing plans for a new UK HQ, after she confirmed there would be no bank windfall tax. The “UK government’s priority of economic growth has been a critical factor in helping us make this decision,” he said.

Carsten Jung, author of an Institute for Public Policy Research (IPPR) paper calling for an £8bn a year tax on the banks, which hit share prices when it was published last summer, said Labour’s anxiety about being seen as “anti-business” had stood in the way of sensible proposals. “We would do well putting a bit less emphasis on business sentiment and a bit more emphasis on economics,” he said.

In the run-up to Reeves’s critical second budget, with the finance sector lobbying intensively against a bank tax, Labour’s business envoy, Varun Chandra, whose role is to smooth over relations with the corporate sector, attended a party hosted by Dimon in New York. The Goldman Sachs boss David Solomon reportedly used a meeting with Reeves to push her personally on the issue.

The executive director of Tax Justice UK, Faiza Shaheen, who was a leftwing Labour candidate at the 2024 election before being blocked by the party’s national executive committee, said: “I think they’re impressed by those sorts of executives, and they’ve been very wary about being anti-business or anti-growth, which for them is the same thing.”

Reeves’s allies reject the idea that she is a pushover in the face of corporate lobbying. One senior government figure pointed out, for example, that she insisted the apprenticeship levy be spent on younger workers, when big business was pushing hard for it to be freed up to spend however they wanted. “These people lobby very hard indeed and it needs resisting,” they said.

Other emails in the Epstein data dump, as well as revealing Mandelson’s role in pushing against the bonus tax, appear to show him aligning with banks as they resisted re-regulation after the crisis that aimed to prevent such a catastrophic collapse ever happening again.

More than a decade and a half on, that struggle continues. As well as eschewing a bank tax, Labour has championed City deregulation as a way of boosting economic growth, with the Bank of England recently announcing it would reduce banks’ capital requirements for the first time since the crisis. Shaheen sighed: “It feels like we’re back in the 90s: didn’t we learn that lesson?”