Hand-Wringing shadow business secretary Chuka Umunna was branded "defeatist" after rejecting an overwhelming Labour conference call to renationalise Royal Mail if the party wins the 2015 general election.

The Streatham MP, who appeared to cheers at the Brighton rally of billionaire-backed right-wing faction Progress last week, took to the internet to reject the popular policy overwhelmingly passed by delegates in the main hall.

Mr Umunna feebly flip-flopped as he used a blog on the Huffington Post website to tear apart the Tory case for privatisation.

"Public ownership helps ensure the taxpayer shares in the upside of any modernisation and future profit that the Royal Mail delivers," he declared.

"The £430 million worth of operating profit the business delivered this year could be reinvested into the business and there is no reason why future profits may not be reinvested in the business too."

But his strident criticism of Tory policy evaporated as he claimed that Labour's hands will be tied once it is sold off.

Its plan was simply to regulate stamp prices, "secure" its universal service obligation past 2015 and more stringent regulation of other private providers, he said.

Campaign for Public Ownership director Neil Clark described Mr Umunna's feeble about-turn as "an uncanny repeat of history" reminiscent of Labour's failure to roll back rail privatisation in the 1990s after initially opposing it.

"It's hugely depressing that it's not prepared to take a step its own conference voted for," he said.

"It's not irreversible. It's not as if it's going to cost too much money.

"If it's bad now, why is it not bad in 2015?"

Pointing to Labour's successful defeat of the coalition government over Syria, he added: "It's defeatist. This government can be defeated.

"Millions of Labour supporters and activists will be hugely demoralised by this after the conference vote.

"Privatisation will destroy Royal Mail - period."

Labour has pledged to table a belated parliamentary debate on the privatisation, while postal workers in the CWU union look set to strike after October 23.

But the government has used the long-winded balloting procedure policed by anti-trade union laws to get a head start.

The City will begin trading Royal Mail shares on October 15.