Home to the Gheorghe Bruna family is a trailer home on a camping site in Maasdriel, a village in the south of the Netherlands. The Romanian family of eleven moved here two months ago, joining the Polish immigrant workers who have lived here for several years. This is what European enlargement looks like up close.

Ionel (26), the eldest son, worked in construction in Spain for two years until demand for Romanian workers there dried up because of the economic crisis. His brother Pedri, who has been here for two years, told him the Netherlands was not a bad place to live. Now, Pedri, his sister and sister-in-law perform as musicians in the streets of nearby Oss.

Hidden group

Almost 2,400 Romanians emigrated to the Netherlands last year - a pittance compared to a total 100,000 migrant workers from Central and Eastern Europe recorded in 2008. But there is a much larger group of people like the Gheorghe Brunas who do not appear in the statistics because they are not registered anywhere.

"It's a hidden group," says sociology professor Godfried Engbersen of the Erasmus University in Rotterdam, where an extensive study about workers from Eastern Europe is underway. The university has hired Polish, Romanian and Bulgarian researchers to seek out the temporary workers and interview them in their own language.

Immigration from Eastern Europe is a sensitive topic in the Netherlands. Last week, candidates in the European elections debated about whether or not Polish, Bulgarian and Romanian workers should be banned from the Dutch job market.

Polish workers are already allowed to work legally in the Netherlands; Romanians and Bulgarians still need a permit, but the borders should soon be opened to them as well.The anti-immigrant Party for Freedom, which won four seats in the European parliament last week, and the far-left Socialist Party want to reverse that decision: they want to keep the Romanians and Bulgarians out and make it more difficult for Polish workers to come to the Netherlands.

The other political parties disagree. "You would think they have the plague," Hans van Baalen of the left right-wing liberal party VVD said about the way PVV and SP talk about the Polish workers.

Slavery

Last month, dozens of Romanians were discovered at an asparagus farm in the town of Someren. According to the town mayor they were held in conditions bordering on slavery. The farmer's lawyer denied the allegations, but the discovery raised the question: was this an isolated incident, or are the Netherlands being flooded with illegal workers from Romania?

Young people are leaving Romania in large numbers because the country is poor. Professor Engbersen: "They used to go Spain and Italy but there are no more jobs there because of the crisis. So they are coming to the Netherlands instead."

Ionel was an electrician back in Romania but he says he couldn't find a job in his field. Even people who have jobs make on average 200 euros per month, he says. In the Netherlands, Ionel makes 500 euros per month by playing the accordion on the streets.

The family's trailer is packed tonight: grandparents, an aunt, two sons, a daughter and a daughter-in-law. four grandchildren and a dog. The youngest children, aged one to seven, play outside the caravan all day. They don't go to school.

The Gheorghe Brunas are allowed to live in the Netherlands because Romania is a member of the European Union, but for all other purposes they are outside the system. If a Dutch employer wants to hire a Romanian or Bulgarian worker, he has to apply for a work permit. The red tape involved means that very few employers go to the trouble. In 2006, almost 3,000 work permits were delivered; 3,600 in 2007 and almost 4,000 in 2008.

16-hour days

The trouble with the work permit is that it makes the worker entirely dependent on his employer. If the employer says he has to work 16-hour days and sleep in an attic together with ten other workers, the worker has no choice but to accept. Those rules will cease to exist for Romanians and Bulgarian next year, just like they did for the Polish in 2007. Ionel, for one, is hoping that the change will go through as planned.

The statistics appear to show that there are fewer illegal workers in the Netherlands every year. Labour inspectors found illegal workers in 16 percent of 10,000 inspections in 2008 - down from 18 percent in 2007 and almost 25 percent in 2006.

The drop is a result of several factors, the inspection agency says. Employers no longer need to apply for work permits for workers from the new EU member states Poland, Estonia, Lithuania, Slovakia, Hungary, the Czech Republic and Slovenia. Spot checks have increased and the number of inspectors has tripled to 180 in the past seven years. The fines have gone up too: an employer now risks an 8,000 euros fine for a first offence and 12,000 euros for a second offence.

But the policy is backfiring, says Dennis Broeders, a researcher at the Erasmus University. The reasoning is that if you make it difficult enough for the employer to hire illegal workers there will be no jobs for them and the illegal workers will leave the country on their own accord. Broeders: "But it doesn't work that way in reality."

Profit margins

There are an estimated 45,000 to 120,000 illegal aliens in the Netherlands, and most of them are working somewhere. They could be cleaning somebody's house, or working in a restaurant kitchen. Broeders: "There will always be companies willing to hire illegal workers."

Westland, an agricultural area in the Netherlands, is one place where illegal workers can still find jobs. Marijke Bijl of the Okia foundation has done research into illegal labour in the greenhouses there. She and her colleagues talked to hundreds of workers who worked illegally in Westland in 2000 and in 1990 for a study, Onzichtbaar achter glas (Invisible behind glass), published in 2004.

In those ten years, the work force change from being mainly Moroccan to mainly Polish. Now, it's mostly Romanians and Bulgarians, says Bijl. She agrees that the number of illegal workers has gone down because of a combination of increased inspections, higher fines and the legalisation of immigrant workers from Poland. But at the same time competition in agriculture has increased too.

Bijl: "The profit margins have shrunk. It is still interesting for employers to hire illegal workers who work hard for little money and who can be put to work during the busy harvesting periods."

Ten years ago it was not uncommon for illegal workers to work for the same employer year in year out. This has now become too dangerous for the employers. "As a result illegal workers are job-hopping and combining different jobs. But even then they make less than the minimum wage." Cleaning houses in the cities is more profitable: it pays ten euros per hour on average.

If Romanians are allowed to work legally in the Netherlands, they will be in a better position to make demands about pay and working conditions like the Polish before them. And then a new wave of illegal workers will take the place of the Romanians, says Broeders. "Ukrainians, Albanese and Africans. As long as there is a demand for cheap labour, they will come."

In the past, migration waves were easier to track, says Engbersen. First came the Indonesians, then the Moroccans and Turkish, followed by their wives and children. After 1975 it was people from Suriname. In the nineties, asylum seekers. Engbersen: "Migration from Eastern Europe is more fleeting. People come and go. Or they stay longer. They are often not registered, working illegally or legally off and on."

Ionel and his brother work six days per week. The police doesn't bother them and the Dutch are kind, they say. But they haven't been able to find jobs in the agricultural sector.

Not having an official job in the Netherlands is not without consequences. No job means no pay check or bank account; which are needed to rent a house. And it isn't easy to find an illegal house for a family of eleven. It gets cold at night in the caravan.

But illegal or not, children are still required to go to school. There is a school in the village. Ionel and Pedri are vague in their answers. Too expensive. The school would ask to see their identity papers. They shrug.