Public services in Britain are hugely overstretched already. The roads are badly congested; There is standing room only on many trains; Hospitals are so stretched that the sick elderly are given short shrift; Housing prices are sky-high and the police have lost control of the streets at night. That is all in theory fixable but the Leftist government spends so much money on bureaucracy that there is little left for anything else. So immigration is going to make an abominable situation worse and all Brits know it. Saying so is another matter, however. You risk being called a “racist” if you do. The way the BNP has been demonized is an excellent example of that

When Karan Whiley, a 48- year-old mother-of-two and care home worker, went to her polling station last Thursday she was in no doubt about the issue concerning her most. “I don’t mind having immigrants who are genuine,” she said. “We live beside an Iraqi couple who have been through hell and are here because they were in fear of their lives. “But these Poles and Lithuanians are taking English jobs. They should stay in their own countries and fight for better jobs there.”

Like many of her fellow residents in the town of Boston, Whiley’s solution to the influx of foreigners — the town’s population has been swollen 25% in recent years by the arrival of an estimated 15,000 immigrants — is to vote for the far-right British National party.

The BNP is particularly strong in this corner of Lincolnshire. Last year the BNP candidate David Owens won a seat on the borough council with a tally that easily surpassed the Labour, Conservative, Liberal Democrat and United Kingdom Independence party votes put together. Last week Owens almost won a seat on the county council — losing by only 16 votes to a Conservative.

The people of Boston are not alone in their concern about migrants. A YouGov poll last month showed immigration as the issue of most concern to voters after the economy. That is unlikely to change in the near future. Figures to be released this week by the Office for National Statistics are expected to show that Britain’s population will expand by nearly 2m during the course of the next parliament alone, almost half because of immigration. It is likely to fuel anxieties about immigrants undercutting wages and putting extra strain on schools and hospitals.

While the mainstream parties squirm and try to avoid the issue, the BNP has been quick to capitalise on it. As well as seeing the election of its first two European MPs in June, the BNP now boasts about 50 local and county level councillors.

Its profile will be further boosted on Thursday when Nick Griffin, its leader, who is an MEP, appears on the BBC programme Question Time. Complaints about Griffin show no sign of abating: on Thursday Alan Johnson, the home secretary, challenged David Dimbleby, the programme’s host, to withdraw the invitation to the BNP because of its “foul and despicable” character.

That was highlighted last week when the party was ordered to change its constitution, which bans non-whites from being members. Such prejudice has led critics to label it neo-Nazi. Griffin reluctantly agreed to consider admitting non-white members only after facing the threat of legal action by the Equality and Human Rights Commission.

Why has the BNP been allowed to pander to the worries of the country without serious competition from the mainstream parties? And why is immigration still the issue that dare not speak its name in British politics?

FRANK FIELD, the Labour MP for Birkenhead and former welfare minister, is in no doubt about the causes of the BNP’s support. “A lot of Labour voters are now voting for them and we have allowed it to happen,” he said. “My only surprise is that the BNP vote hasn’t been even higher. For a lot of people they think parliament has turned their ears off, closed their eyes and sealed their mouths on the big burning issue.”

Field is co-chairman of the cross-party group on balanced migration. The group, jointly led by Nicholas Soames, the Tory MP for Mid Sussex, a former minister and former shadow defence secretary, believes action is needed to stop the population spiralling to unmanageable proportions.

That the population is getting bigger, and that it is due to immigration, is beyond dispute. In 2007 net immigration reached 237,000, although last year it dropped to an estimated 150,000 as the effects of the recession put off economic migrants. According to forecasters, the UK’s current population of 61.4m will grow by 10.5m over the next 22 years, and reach nearly 80m by 2056. “Every million more immigrants means creating a city the size of Birmingham,” said Field. “If we let immigration rise we will have more people sharing less public services.”

His group had calculated that even by 2013 England and Wales will need an extra 96,000 school places, two-thirds of which will be for children with at least one parent born outside the UK. The cost to the taxpayer of providing these places would be £1 billion over five years.

Both Labour and the Conservatives have produced policies to curb immigration. These apply, of course, only to people from outside the EU as those from most of the 27 member countries have the automatic right to live and work in the UK. The Poles and Lithuanians of Boston are here to stay — if they want. Migrants from EU countries are much more likely to visit the UK on a temporary basis for work, and then return home.

Analysis of the latest annual figures suggests that non-EU citizens account for almost 90% of the total of net immigrants, a trend that is expected to continue. Most come from Africa or Asia, with Somalia, India and Pakistan leading the countries from which those seeking British residency originate.