How different the world looks from Bolton West. Yesterday afternoon, when ConHome asked voters there to name the most important election issue, most people said immigration.

Bolton West could hardly be a more marginal seat. In 2010, Labour beat off the Conservative challenge by 92 votes after six recounts. So one might expect that both main parties would have spent the last few years developing something worthwhile to say on this subject which matters so much to electors.

Instead of which, Labour and the Conservatives have confirmed in the last two days at their manifesto launches that they want to talk as little as possible about immigration. There is of course a case for not talking about the subject, or at least for being very careful how one does so. The British Establishment seems to hope the British people will just come to accept the high level of immigration which globalisation and membership of the European Union require.

Immigration is part of the whole question of what kind of a nation we are: a subject which alarms many politicians, even though one of their tasks is to help the nation understand itself. Complaints about immigration are often an expression of economic insecurity, a problem which the parties can claim they are trying to ameliorate. And both main parties may calculate that being trenchant about immigration would end up repelling more voters than it attracts.

But their reticence comes at a price. Our democracy becomes a bit less democratic, and also a bit less interesting. In his diary for last week’s Spectator, Andrew Marr asks why the election campaign is “proving so tooth-grindingly awful”, and replies that the “the parties have chosen to refuse to tell us what we need to know” about the deficit: “It’s sitting there like a great stinking ordure in the middle of public life.”

It is true that a number of expert interviewers, including Andrew Neil, have demanded answers about the deficit, as have a number of admirable economists at the Institute for Fiscal Studies.  But not a single member of the public in Bolton West raised the subject yesterday afternoon.

Here are a few of the remarks made in response to the question “What for you is the most important election issue”, by what could have been termed, if only my research had been more scientific, a focus group (though the number of men and women interviewed was roughly equal):

“Immigration is a big one because that’s getting out of control with the fanatics. We get treated like second-class citizens.”

“If I do vote for somebody, I’m going to vote for somebody who’s going to curb immigration.”

“It needs to be done like in Australia, the points system – so much money in the bank, a certain kind of skill to offer the country.”

Australian methods of immigration control are surprisingly well known in Bolton West. When I expressed amazement at one man’s detailed knowledge (which certainly exceeded mine), he replied that he had seen some reality TV programmes about it on Sky.

A crumb of comfort for the Conservatives could be extracted from these conversations. It appears that in this constituency, Labour voters may be even more tempted than Conservatives to vote for UKIP. It was striking to find Labour often spoken of in the past tense, as the party to which the speaker’s parents had been unwaveringly loyal, but to which such loyalty was no longer possible:

“When I was brought up my Mum and Dad always voted Labour. I used to vote Labour, but I’ve not voted for quite a few years.”

“I remember Tony Blair getting into power and I were over the moon, but more for my father [who was a life-long Labour supporter].”

“Me and my Dad fell out – he was staunch Labour, a pit miner.”

“My friend’s doing a lot of work for UKIP – and she were a big Labour person.”

On the evidence of Bolton West, the Labour Party is as hollowed out in the north of England as it is in Scotland. It is ripe for shaking, but UKIP seems to be the party doing most of the shaking.

The Conservatives possess, in Chris Green, an admirable candidate in Bolton West. A few days ago, David Cameron came here to support him: the picture of a small child with her head on the desk, momentarily overcome by the presence of three camera crews, was taken in a local primary school.

Green said that once the camera crews withdrew, Cameron finished reading the story to the children. Green himself has spent the last two years chasing every local issue he can find, and understands the seat very well. In April 2013, when Paul Goodman pointed out on this site that “Margaret Thatcher’s legacy should be a Conservatism for Bolton West”, Green followed up with a piece in which he identified immigration control as one of the key issues.

If all goes well for Green, then for Bolton West this will be another 1983. The constituency (under somewhat different boundaries) declined to turn Tory at Thatcher’s first victory in 1979, but did so in 1983, when Tom Sackville won the seat, which he held until the Blair landslide in 1997.

From an economic point of view, there are grounds for optimism. Green points out that in the last year and a half, unemployment in Bolton West has gone down by a half. People want the recovery to continue. A regeneration scheme costing a quarter of a billion pounds has begun at the former Locomotive Works in Horwich, one of the main towns in the constituency.

Incidentally, most of Bolton West is not in Bolton. The seat consists of a number of separate towns and villages between Bolton, Chorley and Wigan. People who live here often feel in danger of being left behind by their larger neighbours, and are also angry, at least among the older generation, that instead of remaining part of Lancashire, they were incorporated, under the wretched Heatho-Walkerian reforms of the early 1970s, into Greater Manchester.

These conversations were carried out in Horwich, two stops on the railway beyond Bolton, and suggest a very complicated electoral picture. In 2010, Labour got 18,327 votes, the Conservatives 18,235, the Lib Dems 8,177 and UKIP 1,901. The Lib Dems have since collapsed, to the benefit of Labour, but UKIP has made a strong advance, and has perhaps damaged Labour more than the Conservatives.

Many people in Bolton West have not yet decided who to vote for. A school caretaker said:

“My gut instinct is to vote for UKIP. But when I read the newspapers they sometimes make out it could be a vote for Labour and I don’t want Labour to get in. I think Miliband’s s*** [laughter].”

Although several people expressed contempt for Miliband, straightforward declarations of support for the Conservatives are not yet as numerous as one would expect if the party were about to defeat Labour in Bolton West. Minds will need to become much more concentrated if that is to happen. But are the current generation of party leaders capable of impressing themselves on voters here? A woman said:

“Bring Margaret Thatcher back. She didn’t mess about when the Falklands happened.”

And a man commented:

“I’d just like to see someone grow a bit of a backbone. I’m putting it politely.”