GMB members have warned Labour’s “unbelievable” decision to keep the two-child benefit cap will make voters switch to the Lib Dems.

A motion condemning the policy, which prevents parents from claiming benefits for more than two children, was passed at the union’s annual conference today.

It noted: “Unbelievably, last year Sir Keir Starmer decided that scrapping the two-child benefit cap would no longer be Labour Party policy, despite the estimations that this would lift around 270,000 households with children out of poverty.”

Three Shires delegate Martha de Bruxelles said the Lib Dem manifesto promise to scrap the cap will “certainly alienate” voters from Labour.

Central executive committee member Gordon Richardson said the policy remains a “cruel element of the failed austerity doctrine of the Cameron-Osborne years” and that “alleviating child poverty should be a priority for the next government.”

Delegate Jenny Howard added: “This is shameful, we are reverting back to Victorian England.”