Keir Starmer's alleged data breach is the latest battle in a civil war that is paralysing Labour

Corbyn critics want to end the sectarianism that marked his leadership, but this controversy is prolonging it

On the day Jeremy Corbyn was elected Labour leader in 2015, some party staff wore black to register their dismay that the left-winger had won. Initial relations between LOTO (the leader of the opposition’s office) and some HQ officials were frosty.

Over time, staff unsympathetic to the Corbyn project either left or were weeded out. The process was completed when Jennie Formby became general secretary in 2018. The left now controlled the party machine – its national executive committee, main trade unions, leadership – even if it did not dominate among Labour MPs.

Corbyn’s allies, who had been long consigned to the wilderness, were determined to learn from one of Tony Blair’s mistakes. After winning power in 1997, he lost interest in internal party reform. By contrast, left-wingers would proceed to cement their grip after 2015.

Before December’s general election, the left was confident it would retain the leadership if the party lost. While it was an open secret that Corbyn would stand down in the event of a defeat, Laura Pidcock was tipped as the new standard-bearer – until she surprisingly lost her North West Durham seat, when Rebecca Long-Bailey became the new favourite.

Yet the left’s dominance of the party is now under threat. The scale of Labour’s defeat has contributed to a surge in support for Keir Starmer, leaving Long-Bailey trailing in his wake. Many party members, including some natural Corbyn supporters, appear to put winning power in the country ahead of retaining power in the party. The change was symbolised when Corbyn’s Islington North constituency party backed Starmer. He has now won nominations from 279 local parties, compared to 131 for Long-Bailey, 56 for Lisa Nandy and 18 for Emily Thornberry, who seems unlikely to secure the 33 she needs by Friday to make the final shortlist.

The left will not surrender without a fight. According to Starmer’s allies, that is the only explanation for Labour HQ reporting his campaign to Britain’s data watchdog, and accusing two of his staff of hacking into Labour’s membership list. The Starmer camp insists the pair tested a possible breach of rules by Long-Bailey’s team, which had reportedly sent an email to supporters enabling them to access the list. Her aides say this was done innocently. Starmer’s campaign reported the matter to party HQ, but did not get a reply. Later, they were shocked to discover that Starmer, rather than Long-Bailey, had been reported to the Information Commissioner.

The contrast with Labour HQ’s handling of another possible breach of the rules by Long-Bailey was marked. The Independent revealed last month that she was let off for allegedly promoting campaigns to her local members using party data.

This might sound like an obscure procedural row, but Labour’s 500,000-plus membership list is gold dust. Access to it enables campaigns to canvass members – for example, through phone banks. There are fears the complaint against Starmer might be used to deny him access to the list when it becomes available to candidates on the shortlist.

“Labour HQ should be neutral but there is no level playing field,” one prominent Labour centrist said. “The party machine is using every trick in the book to try to stop Keir. It clearly senses the game is up.”

Some Corbyn critics are less confident, fearing the party machine – with support from the grassroots group Momentum and the Unite union – might yet deliver for Long-Bailey. If that happened, there are growing rumblings that 30-40 Labour MPs would quit the party.

While the data dispute could affect the outcome, it is hardly a positive signal to any voters tuning in to Labour’s post-election debate. The party appears to be turning on itself rather than learning the painful lessons of its crushing defeat. Corbyn critics want to end the sectarianism that marked his leadership, but this controversy is prolonging it. If Starmer wins, it will now be very difficult for him to work with the current HQ regime.

Perhaps it was inevitable the candidates would pull their punches on Corbyn, who retains the respect of the members whose votes they need. Nandy deserves credit for outlining plans to tackle the “crisis in the soul of our party” on antisemitism. Starmer has the natural caution of the front-runner but is perhaps missing a chance to start the long haul of winning back the public. Candidates send members reassuring messages about Corbyn being right on ending austerity. That is not exactly bold: even the Conservatives want to end austerity.

Labour’s would-be leaders could and should be a little more open about the reasons for Labour’s worst defeat since 1935, which include Corbyn’s own performance. If Labour can’t even be honest with itself, it will not regain voters’ trust.