Thurrock is regarded by bookmakers as the second most-winnable seat in the country for UKIP, but immigration is barely mentioned by candidate Tim Aker as he canvasses voters.

Instead, the strategy is to win-over residents by offering help with more mundane issues, such as broken boilers, mould and damp and weekly bin collections. “Our concern is their wellbeing,” said Chris Baker, a UKIP councillor, as he led a canvassing team in South Ockendon.

Much of Thurrock is deprived, and UKIP appears to be winning support from those out of work or unable to work. Its anti-establishment status resonates among voters alienated from mainstream politics.

“We have got an awful lot of people who have never voted before,” Mr Baker said. “They look at our issues and the way we go about things, and now they’re voting UKIP.”

Mr Aker, 29, is a UKIP councillor and MEP for the area. He plays up his local credentials – he is Thurrock born and bred – and tells voters that Labour candidate Polly Billington (a North Londoner who moved to Grays in 2011) and sitting Tory MP Jackie Doyle-Price (who was born in Sheffield) are outsiders.

“The Conservatives won here [in 2010], but not because of any support for Cameron,” Mr Aker said. “They held their noses and voted for the person who was going to get Labour out. There is now a new option on the ballot paper, and people are coming to it.”

But Ms Doyle-Price insisted a UKIP victory was not on the cards. She predicted UKIP would gain no more that “a quarter” of the votes, with the winner gaining a third.

She promised to do all she could to stand up to UKIP. “These people are unpleasant,” she told me. “They have unlocked a nasty vein of prejudice in our country.

“The Conservative party has nothing in common with UKIP. I would rather stick pins in my eyes. They are not going to win here – not in a million years. They are very good at talking a good game and [the media] is buying it.

“The UKIP vote is the white working class in areas that were traditionally Labour. Local elections in the last year where UKIP made gains were in areas where you would traditionally weight the Labour vote.”

Ms Billington, who was selected as Labour candidate in 2011, followed 15 years at the BBC by becoming a press aide to Ed Miliband. Mr Aker says she refuses to debate the closure of Tilbury power station, which he claims is a legacy of Mr Miliband’s time as Energy Secretary. “It’s the behaviour of a parachuted-in candidate,” he said. “I’m not just here for the photo opportunity.”

The contest shows every sign of being fiesty. During the Standard’s visit, Mr Aker’s team found one voter, Kaye Pearson, 30, a single mother, who claimed to have been duped by Ms Billington into backing Labour and having a poster attached to her balcony.

She invited Mr Aker and Mr Baker into their home to ceremonially cut down the poster for the Standard’s photographer. “I’m going to hand-deliver it back to Labour,” Mr Aker said. “Keep Britain Tidy, and all that.”

Ms Billington denied she misled Ms Pearson. “Clearly she has changed her mind [about the poster],” she said. “I’m not going to exploit an individual voter. I think it’s pretty shoddy if UKIP are doing that in these circumstances.”

When Ms Billington was selected, the task looked easy for Labour. Ms Doyle-Price’s majority was only 92, and UKIP had won just 7.4 per cent of votes in 2010.

Ms Billington – who is wearing a grey plastic boot after breaking her right foot “exaggerating my stride” for a photographer – admits the rise of UKIP as an “opportunity to stick two fingers up to the political establishment”.

Edwina Aldwinckle, who will be voting UKIP, said: “I don’t like Labour and I don’t like the Conservatives. UKIP have got people who live round here doing a good job.

“People like us, we can not get better jobs, we can not get the houses. When people come over from different countries, they get dole money, they get our houses, they are getting all our benefits.”

Peter Perrin, a retired staff sergeant in the Royal Corps of Signals, backed UKIP for two reasons: “Controlling immigration, and the Veterans’ Charter.”

He said: “If we don’t maintain our freedoms, we will end up governed from another country, and those people who sacrificed their lives in two World Wars and before will be turning in their graves.”

Amanda Flatt, 36, was voting UKIP: “It’s the fact they are more for us guys than anybody else.” She added: “I used to vote Conservative but they have messed up the Government.”

John Archer was a lifelong Labour supporter but had deserted the party for UKIP: “The way the country is going, instead of going up, we are going down.”

Fred Morgan stopped his car to plead with Ms Billington to “tidy-up Tilbury” and tackle anti-social behaviour. Stuart Radford said he may “possibly” vote Labour after she pledged to address fly-tipping in a field beside his home and yobs who set fire to his wheelie-bins.

But Sharon McKinsey likes Nigel Farage and is backing UKIP. “I just want to give them a go,” she said. “He seems down to earth, in the pub smoking and drinking. It shows they care about us.”

Ms Billington insisted it was a three-way fight – a strong Tory vote could help her chances. She believes voters will desert UKIP nearer polling day when they focus on who they want as Prime Minister.

She makes a determined effort on doorsteps to challenge voters who say they are voting UKIP. The Labour door-knocking campaign is slick and Ms Billington comes across as a heavyweight political operator, a Government minister in the making.

She believes she has a duty to make voters aware of the consequences of backing UKIP – explaining its policies on the NHS, and the likely effect of helping David Cameron get back into No10. “I think you have got to do right by people,” she said.

She tells one voter: “I’m Labour because I have the same values as you. I want to narrow the gap between rich and poor.”

Voter John Archer asks why Labour does not support an EU referendum. “I think we can make Europe work for us,” Ms Billington said. “Nigel Farage would just walk us off into the Atlantic Ocean.”

She accuses Mr Aker of double-standards. “When you look at Tim Aker’s voting record in the European Parliament, he didn’t bother to turn up to vote against casualisation, including zero hours contracts. When he gets the opportunity, he fails working people.”

She continues: “For a lot of people here, they don’t want a Tory government. What really annoys me is that you can see the Shard and Canary Wharf from Thurrock, but for many people it might just as well be the Emerald City.”

* An edited version of this article appears in today’s Evening Standard.