The new “People’s Assembly Against Austerity” will march through London on 22 June, and, with the help of the Stop The War Coalition, intends to break that group’s record for the largest public rally in the nation’s history.

Backed with trade union cash, and fronted by comedians, unionists, activists and MPs from different parties, the group claims it will be “an alternative democratic forum to a Parliament that has failed the people it is supposed to represent.” It will be, they hope “the launch-pad for mass resistance to austerity”.

The Green Party MP, Caroline Lucas, Labour’s Katy Clark, the Director of Executive Policy at the Unite trade union Steve Turner, the head of the National Union of Teachers Kevin Courtney, comedian and disabled activist Francesca Martinez, as well as Independent columnists Owen Jones and Mark Steel, are the figureheads of a group they hope will appeal to anyone against austerity, regardless of background.

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“We are not radicals,” said Francesca Martinez, who is most recognisable for her role in Ricky Gervais’s Extras, “the Government are the radicals. Stop people in the street and ask them are you in favour of the NHS, for example, and they will say ‘yes’”.

The People’s Assembly are of the view that there is an alternative to austerity which is not being articulated by the three main “corporate-led” political parties, or “corporate-led” media.

John Rees, a national officer for the Stop The War Coalition, said the planned march on 22 June would “have to be bigger than the ‘stop the war’ march”, which took place on the 15 February 2003, in protest at the growing likelihood of an invasion of Iraq, a march which “we now know” he says, “came very close to stopping the war”. Estimates for numbers at that rally range from 750,000 to 2,000,000 people.

This movement, its leaders hope, will create momentum “powerful enough to generate successful co-ordinated action”.

“If you’ve ever yelled at the television while George Osborne is on, or fumed at how the poor are made to pay for the mess created by the bankers,” comedian Mark Steel said,“sign up to the People’s Assembly”.

The group represents a challenge not just to the governing Conservative and Liberal Democrat parties, but also to Labour, whose “austerity light” they feel does not represent a credible alternative. It is astonishing, they argue, that five years on from the global crash there is there is no mainstream alternative to austerity, and this group will fill a chasm in British politics.

Among its backers are the former Labour Cabinet Minister Tony Benn, several Labour MPs and the heads of the country’s largest trade unions.

The filmmaker Ken Loach has also supported the group, in the wake of the release of his Spirit of ‘45 film, which evokes the tenacity of a Labour Government who took over a tired country at the end of the Second World War, but who nonetheless set up the NHS and the welfare state.

Loach has expressed a lack of faith in the current Labour party achieving anything similar, as has Len McCluskey, the head of Unite.