The big society: Mr Pickles heads to the marginals to sell revolution

It is shortly before 4pm outside a busy Asda store on the outskirts of Sheffield, and the Eric Pickles Battle Bus has just drawn into the car park for a round of canvasing.

The Conservative Party chairman's campaign vehicle – it is actually a people carrier with the slogan "Vote for Change" emblazoned on the side – is attracting beeps from the cars of fellow shoppers.

Are these hoots of approval? No. The bus is, momentarily, in the way of a line of cars. Families doing the weekly shop don't have time to wait.

Mr Pickles, the straight-talking Yorkshireman in David Cameron's top team, has come home to rally candidates in a string of marginal seats the Tories need to win on 6 May to secure victory. But he's also spreading the word about the Conservatives' grand idea, unveiled in the manifesto two days earlier: the "Big Society".

A Tory government will send out a 5,000-strong army into the country to stimulate "social action" projects, such as community gardens, while teenagers will be encouraged to enlist in a new National Citizen Service to carry out voluntary work.

At the same time, residents will be able to take over post offices and pubs threatened with closure, parents unhappy with their child's school can set up a new one, and there will be the option of referendums for people unhappy with local services.

The Big Society will not replace the state, but it will hand over more responsibility to individuals and communities. But critics say it is a Thatcherite cover for swingeing cuts to frontline public services, and question if people have time to get stuck in.

Mr Pickles insists the change – a "revolution" – will become a reality within one term of a Tory government: "Any real revolution, unless it's a violent revolution, is going to be gradual. [But] I would be very upset, I would regard it as a failure, if by the end of a full term in Parliament, it wasn't self-evidently different.

"I would be really cheesed off if, by Christmas time, we couldn't point you to two or three really good examples of it taking off."

Judging by a day's campaigning in three Tory targets in West and South Yorkshire, the electorate is going to need some convincing.

The Asda store where the Pickles bus is parked is in Chapeltown, a working-class suburb on the northern outskirts of Sheffield and part of the Penistone and Stocksbridge constituency, where the Labour MP Angela Smith is defending a notional 8,849 majority.

Walking into the supermarket is Anne Doyle, 49, an accountant, and her young daughter. Mrs Doyle is planning to vote for the Conservative candidate, Spencer Pitfield, after backing Labour all her life. But she is deeply sceptical of Mr Cameron's Big Society plan.

"I don't like the idea of taking over schools," she says. "I just don't see how it could work. It will work in some areas, if you have got a strong set of good parents. But not around here."

Despite her decision to vote Tory next month, she adds she is "not quite 100 per cent" about Mr Cameron and the Conservative Party.

I put it to Mr Pickles that the Big Society argument, getting people to do things for themselves, is merely Thatcherism with a new gloss.

But he says: "This is not about the power of the individual, this is about the power of the people to be able to work together to change society. We now have 130 social action programmes up and running – not only have they changed the perception of our party, they've changed the reality."

Earlier, the Pickles bus took the bumpy journey to Colne Valley, a three-way marginal constituency in beautiful West Yorkshire countryside. Colne Valley has been a Labour seat since 1997, but before then it was Conservative. It is Tory target number 27, and Lib Dem target number 40.

Patrick Tate, associate director of the socio-demographic analysts CACI, says the constituency is typical of the kind of marginal that will hold the key to winning the election.

One in five people in Colne Valley are classed as blue-collar "recession strugglers" – one of three groups identified by CACI that are over-represented in the crucial swing seats. The other two groups are the "New Labour Generation" of young, educated urbanites and "Traditional Englanders", who are older couples on middle incomes with a strong interest in domestic affairs. So if anywhere is going to be a good place to gauge reaction to Mr Cameron's Big Society, it is here.

At Hinchliffe's Farm Shop and Restaurant in the village of Netherton, Irene Firth is ordering a quarter pound of mince from the butcher when Mr Pickles, the Tory candidate Jason McCartney and a stream of activists wearing blue rosettes walk in.

Mrs Firth, 62, a retired publican and grandmother, has always been a Labour voter, but is now not sure who to back. She is not yet convinced by Mr Cameron. Does she think the Tory plans for a Big Society will work?

"I think people on the street need to be a bit more co-operative. People used to keep their doors open and the neighbours all knew each other – that has gone out the window.

"Fifteen years ago, I would have knocked on the door to see if they needed anything. Now I don't do that because there is a different attitude. It has got a bit scary."

Further north, in Bradford West, a seat with a large Asian community, Mr Pickles canvases with the candidate Zahid Iqbal, who hopes to overturn the notional 2,580 majority of the sitting Labour MP, Marsha Singh.

Naveed Akhtar, 24, an IT technician, answering the door of his terrace home in Frizinghall, gives Mr Pickles the thumbs up and tells him: "You have definitely got my vote."

But after they move further up the road, I linger to ask what he thinks about David Cameron's Big Society.

"I am only going to vote on local issues. That's a hard question. I need to read up on that a bit more. I am not 100 per cent sure about that."