Labour leader says he has exchanged texts with business secretary and is 'open for business' with him

Ed Miliband has moved to exploit tensions within the coalition and among Liberal Democrats by declaring he is "open for business" with Vince Cable, who describes himself as the cabinet's only social democrat.

As supporters of Nick Clegg express growing irritation with Cable, dubbed leader of the "Continuity SDP", the Labour leader said he had recently exchanged texts with the business secretary.

"Open for business," Miliband said as the shadow chancellor, Ed Balls, explained in a joint appearance at a Policy Network conference how Labour was willing to talk to Cable, who was an adviser to the late Labour leader John Smith when he was a cabinet minister in the 1970s.

Balls said he would be happy to talk to Cable about his proposal, drawn up by the Lib Dems' former Treasury spokesman Lord Oakeshott, for a mansion tax on properties worth more than £2m. "We said [at the time of the budget] that we didn't think a mansion tax to fund top-rate tax cuts was a good idea," Balls said. "But if Vince Cable or George Osborne wanted to have serious discussions with us about a cross-party consensus on a mansion tax for good and fair and long-term purposes that is a discussion we would like to have."

As the audience laughed, Balls added: "The conclusion we have reached is George Osborne doesn't want to have that discussion at all. Nor does Nick Clegg. But if Vince Cable would like to sit down and have a serious conversation about how we can make our economy work for the long term then we can have that discussion."

At this point Miliband intervened to say: "Open for business."

The Labour leader also acknowledged that he had been in text contact with Cable. "I exchange texts with lots of different people. Wisdom doesn't reside in one political party … [But] the Liberal Democrats made a tragic mistake [on the deficit]. I welcome all people who recant."

Balls joked: "Exchanging texts is always a dangerous thing."

Danny Alexander, the Lib Dem chief secretary to the Treasury, said Cable had exchanged one text with Miliband over House of Lords reform.

Miliband and Balls made a joint appearance at the Policy Network conference, held at the London Stock Exchange, to launch the start of the new political year with a fresh approach on the economy. This is known as predistribution, in contrast with the traditional centre-left approach of redistributing wealth from the rich to the less well-off.

In his speech Miliband said that a Labour government would always believe in redistribution. But with less money to redistribute a Labour government would focus attention on pushing up wages by equipping the workforce with better skills.

Miliband said: "The redistribution of the last Labour government relied on revenue which the next Labour government will not enjoy. The option of simply increasing tax credits in the way we did before will not be open to us.

"Of course, redistribution will always remain necessary. But we've learned that it is not sufficient.

"We need to care about predistribution as well as redistribution. Redistribution offers a top-up to wages [of the low paid]. Predistribution seeks to offer them more: higher skills, with higher wages.

"Centre-left governments of the past tried to make work pay better by spending more on transfer payments. Centre-left governments of the future will have to also make work pay better by making work itself pay."

Miliband also launched a strong attack on Osborne for adopting a "wrong-headed" approach on the environment. "The current chancellor poses the environment and the economy as, essentially, alternatives," he said. "So either you can have a successful environment or you can have a successful economy. That is totally wrong-headed. We know that a lot of the future jobs in this country will come from the green industries of the future."

John Sauven, executive director of Greenpeace, said: "George Osborne must stop holding back Britain's low-carbon businesses. Everybody from the CBI to the Labour leadership to green groups are now urging him to back these growing industries. This sector provided around a third of all growth in the economy over the past year, and Ed Miliband is right to highlight how it should be central to our economic recovery."

Oakeshott said: "Liberal Democrats will welcome support for the Liberal Democrat manifesto commitment to a mansion tax wherever it comes from, even from Ed Balls the prodigal son. But the wealth gap widened to a yawning chasm in his years at the Treasury and he wouldn't say boo to a non-dom goose."