Since May 2004 10 Eastern European nations have joined the European Union.
The UK was one of the few countries to give most of these country's citizens free access to our labour market - although there are restrictions on Romania and Bulgaria which joined the EU in January 2007. So what do we know about what has happened during the past two years?
The figures are incomplete, not least because the situation changes by the day, but there is enough information to some of the trends in the arrival of workers from Eastern European states.
WHO ARE THE WORKERS?
The eight nations given unfettered access to the UK's jobs market in May 2004 were the Czech Republic, Estonia, Hungary, Latvia, Lithuania, Poland, Slovakia and Slovenia, known as the "Accession Eight".
Two other nations joined the EU on the same day - Malta and Cyprus - but their labour force is tiny and not subject to any potential restrictions.
Along with other EU member states, the UK had a choice. It could either open its doors to workers or use restrictions for up to seven years.
Between May 2004 and June 2007 683,000 people from the "Accession Eight" nations registered to work in the UK.
We cannot say whether all or just some of these workers are in the UK at the moment.
Anecdotally, we know many workers come for short periods - but others certainly stay for a lot longer.
Over the first two years, the trend has been marginally upwards but has now levelled off.
In the first quarter after accession, 42,000 people came to work in the UK. The peak so far has been the fourth quarter of 2006 when 65,000 came to work, contributing to a total of 227,850 for the year.
The first half of 2007 saw a fall in numbers - 52,000 in the first three months and just under 50,000 between April and June.
By far and away the largest group of people coming to the UK has been the 430,400 Polish workers. They make up seven out of every 10 Eastern European workers in Britain.
The next largest group are Slovakians. The smallest groups are Estonian and Slovenian.
As for the new joiners Bulgaria and Romania, relatively few of their workers have registered in the UK - some 9,500 in the first six months of 2007.
While the government massively under-estimated the numbers who would come, experts advising Whitehall did at least correctly predict what types of workers would come.
The expectation was that those who would make the trip would tend to be younger, tallying with recognised economic migration trends.
Four out of 10 of the workers who have come to Britain have been under 24. A massive 80% have been under 34.
After that age, the numbers drop off steeply, almost certainly because people settled with families are less likely to move than those who are single or childless. This is a key factor to watch for the future.
WHERE DO THEY GO?
However, this time around the destinations have been more varied as workers have gone to entirely new areas short of labour.
The early signs of this were clear in the mass arrival of Eastern European and Far East manual labour into agriculture during the past decade.
This has meant that areas of the country unfamiliar to large-scale immigration, such as East Anglia and south-west England, have experienced it for the first time.
This trend has continued. The latest available figures show that unlike during other periods, London is no longer the top destination for migrant workers.
Anecdotally, some employers and local authorities think that a key factor in where people turn up may be the growth in no-frills airlines into Eastern Europe from regional British airports, meaning employers looking for cheap and temporary labour can use agencies to bring people in more quickly than before.
WHAT TYPE OF JOBS?
The government has stressed that Accession Eight workers have been filling what it says are gaps in the labour market, particularly in near minimum wage industries such as food, catering, agriculture or manufacturing and production.
The reality is far more complicated.
Factory workers comprise 37% of the total number of workers over first two years, but many workers have now gone into administrative, business and clerical jobs, alongside influxes into the catering and hospitality industries.
Transport has seen some substantial numbers - 16,000 workers over three years. Some 21,000 workers have gone into construction.
Some 97% of registered workers were found to be working full time and the majority, as expected, were earning on the lower end of the scale - between minimum wage - currently £5.10 - and £6 an hour.
A SOCIAL IMPACT?
This remains one of the most controversial areas of migrant working because it is very difficult to calculate the costs on the state compared with the benefits of taxes raised. However, we do have some figures on benefit take-up relating to the registered workers.
According to the government, the numbers who have sought benefits and housing support have been "low".
Between April and June 2007, some 3,785 people applied for Income Support and the Jobseekers Allowance. Only 936 were deemed eligible for consideration. In all, 3,600 A8 nationals have successfully applied for income-related benefits since May 2004. A further 800 had homelessness support.
The figures also show a demographic shift taking place among the workers. The number of registered workers with children in the country had reached 20,000 at the end of 2006 with a further 9,000 in the last six months.
However, a separate figure shows that 68,927 have been approved for child benefit payments and 38,578 for tax credits (aimed at families) indicating that there are many workers who are not counted in the worker registration scheme figures.
This indicates that some workers who want to stay are probably bringing their families into the UK.