Dave Ward, the CWU general secretary, said on Wednesday: “I don’t think any union that is in contention at the moment has the support of the Labor leadership. Their actions – Keir Starmer’s actions – in this are disgraceful and unacceptable.” The Telegraph understands concern extends to more moderate unions that have yet to make public statements, including Usdaw, the shop union, and Unison, which was Labour’s biggest financial backer last year, donating almost £1.8m. A Labor source said: “There is a real feeling now that this could be a very important moment. There could be a permanent rift with the other unions. Starmer has p—– off basically the whole TUC [Trades Union Congress]. The party could go bankrupt, which almost happened in the past.” Sharon Graham, Unite’s general secretary, issued a furious statement on Wednesday night, calling Mr Tarry’s sacking “an insult to the trade union movement” and saying: “Attacks by minors on trade unionists will do absolutely nothing for to advance Labour’s prospects. power.”

‘Absolutely outraged by what happened’

The Telegraph understands that while Unite is unlikely to fully break away from Labour, it is unlikely to contribute more than the minimum in donations. “Sharon is absolutely outraged by what happened,” a source said. “Why should I? [Unite] give millions of pounds a year to the Labor Party when they don’t have the support?’ But speaking on a visit to Birmingham on Thursday, Sir Keir appeared to play down the break with Unite, saying: “The Unite union and the Labor Party have a very strong relationship. I am a member of Unite. This relationship is historic, it is present and it will be the future of the Labor Party. “They’re working with us on our bill of rights at work, which is, you know, the most comprehensive set of rights at work that we’ve ever seen come out of the Labor Party.”