How hard is it for immigrants to learn English? The project was filmed as part of a two-part Channel 4 documentary, Why Don't You Speak English?, which starts on Tuesday. Cameras follow four recent migrants as they stay with host families in an attempt to brush up on the language. A Chinese migrant is filmed being taken on an entirely mimed tour of Redcar, and a Colombian removal man learns phrases from a Northern Irish landlord in a Chelsea pub. All four are frustrated by their failure to learn quicker. "It really disturbs me," says Sifa. I'd like to able to talk to other people but I can't. The film is timely. According to the most recent census figures, published in March, 4.2 million people who live in England and Wales do not have English as their "main language," with 546,000 speaking Polish. Of that number, 726,000 people said they could not speak English well, and a further 138,000 said they did not speak it at all. In the London borough of Newham nearly one in ten people either speak the language poorly or not at all. Politicians have pledged to tackle the issue. Ed Miliband, the Labour leader, promised that if he were Prime Minister, teaching immigrants would be "more of a priority than providing many written translation materials in foreign languages" and he would ban those who could not speak the language from taking public sector jobs. In last month's comprehensive spending review, George Osborne responded by insisting benefit claimants will now have to attend language courses. "It will help people find work," he said. But if you're not prepared to learn English, your benefits will be cut. According to those who teach the migrants, however, these measures alone will not solve the problem. "There's a dissonance between the rhetoric and the facts," says Judy Kirsh, chairman of the National Association for Teaching English and Other Community Languages to Adults. It sounds great that everyone must learn English, and nobody disagrees with that. The problem we have is over funding. Two years ago, the Government tightened up on the subsidies it offers migrants who take basic English classes, called English for Speakers of Other Languages (ESOL). Now only those on jobseekers" allowance or employment support allowance automatically get the lessons for free. Others can be asked to fund half of their course, which cost up to £1,000. "It means housewives who are not working but are not on benefits have to pay," explains Kirsh. Many of them cannot afford it. It is very costly to provide free tuition, but you've got to weigh that against the cost to the economy of people not speaking the language. The figures appear to bear out her claims. The number of adults taking ESOL courses has nearly halved in the last seven years, to only 163,000 people in 2010. Enrolments fell by a further 24,000 the next year, when the Government's new funding regime was introduced. The Scotts wanted to test how much English it was possible for a migrant to learn in a week, and were pleasantly surprised by the results. "This was much more intensive than her classes because she was here from dawn to dusk with us talking English the whole time," says Robin. When she arrived she had a few isolated words and by the time she left she was to the point of stringing words together. Her tutor [at the language school] said he had noticed a big advance in just the short time she was with us. The couple hope to keep in touch with Sifa, and have encouraged her to get the bus from Sheffield to visit. Robin accepts, however, that few families are likely to be able to afford to host a new immigrant. "But I would like to see some formal arrangement for every migrant to have the opportunity to learn for free and be required to achieve a certain level," he says, as his working golden retriever, Lola, chomps loudly on a bone. You should not be able to extend your visa beyond a year unless you've passed the test. The couple have form in teaching in English. Their film-maker son, Roddy, was killed, aged 31, making a film about the conflict in Chechnya in 2002. A few years later, they flew out to visit the refugee camp in the Georgian village of Pankisi where he had made his final documentary. "We were overwhelmed by the number of people in the village who knew him," says Robin. We were impressed by the stoicism of all of them and we felt if there was something we could do to help, we would like to do it. What they really wanted was to learn English; first of all we investigated helping a non-governmental organisation but then we decided just to get on with it. They set up a charity in 2008 and now employ four teachers at their school in Pankisi, which teaches 200 refugees aged 12 to 16. Robin cannot help contrasting the fluency of the children in a remote part of Georgia with the increasing number of migrants who struggle with the language back in Britain. "It is an irony," he says. The first thing the Georgians want to know is how Manchester United are doing. But here, some migrants are living in a community of other Poles and can get by, so what is their motive? We are very relaxed about immigration. Roddy used to say, 'the history of the world is the history of migration. It is inevitable, but integration is the important thing. You can't do that unless you speak the language. 'Why Don't You Speak English?' is on Channel 4 at 9pm on Tuesday