Two years after EU enlargement, Finland, Greece, Portugal and Spain have joined the UK, Ireland and Sweden in lifting employment restrictions on workers from the eight new member states from Eastern and Central Europe.
But the pattern of migration over the past two years indicates that nationals of some of the new member states will be taking up these opportunities in much greater numbers than workers from the others.
Since they lifted restrictions, the UK and Ireland have provided employment for just over 500,000 citizens from these eight countries.
In fact, these figures are likely to be a big underestimate.
In the UK's case, the available statistics are not particularly up-to-date: they include figures only up to the end of 2005.
And they are based on a system of registration which, in practice, many workers from the new member states ignore, partly because of the costs and bureaucracy involved, partly because they may wish to avoid paying tax.
Whatever the level of accuracy of these statistics about the overall number of workers, the British and Irish figures show a degree of consistency when it comes to the national origins of these migrant workers.
Poles account for 300,000 workers - 60% of the total.
That is hardly surprising since Poland's population is just over half that of the total for the eight countries.
Much more pronounced is the huge proportion of workers from Lithuania and Latvia, two countries with very small populations, that account for about 110,000 workers - about 25% of the total.
By contrast, workers from another Baltic state, Estonia, hardly figure in the statistics - under 2% of the overall figures.
There are even fewer from Slovenia. Proportionately, only a relatively small number of Hungarians and Czechs have made the journey to the UK or Ireland.
Wealth gap
Aidan Manktelow, a Central Europe specialist at the London-based Economist Intelligence Unit, says much of it has to do with economic conditions at home.
"There are actually quite big discrepancies in the relative prosperity of the new member states. On the one hand, you have countries like Poland, Latvia, Lithuania and Slovakia - their GDP per capita is about 50% of the EU-25 level. That compares with about 60%-80% for the Czech Republic, Hungary and Slovenia.
"And bearing in mind that much of the migration is probably temporary - at least in intent - the money that can be saved up goes much further in, say, Poland than it would do in Hungary."
This argument is certainly backed up by the evidence from Slovenia, where living standards are on a par with those in many of the older EU members; therefore few Slovenes feel the need to find work elsewhere.
And those who do may prefer to work - or commute to work - nearer, say in Austria, if they can obtain a work permit.
Commuting to work has also become a habit for Slovaks, particularly those living in Bratislava or its neighbourhood - barely an hour's drive from Vienna.
The fact that work permits may not be easy to obtain has not put off many Slovaks - nor has it stopped some half a million Poles finding employment in Germany, many of them in seasonal agricultural work.
Home employment
When it comes to deciding to work abroad, employment prospects at home are another crucial factor, says Aidan Manktelow.
"Poland, Slovakia, Latvia and Lithuania have generally higher rates of unemployment than the other new member states.
"That's especially the case in Poland and Slovakia. These countries have much larger rural sectors than the Czech Republic, Hungary and Slovenia. And the result is that there's a very large pool of unskilled workers."
Poland's unemployment - at nearly 18% the highest in the EU - is a powerful incentive for its workers to seek jobs abroad.
And they have moved to the UK in such large numbers that a senior British diplomat last year noted, somewhat controversially, that the UK had created more jobs for Poles since May 2004 than Poland itself.
For Lithuanians, the job opportunities of EU membership have brought an even bigger benefit. They have contributed to halving the unemployment rate from 8% two years ago.
Support network
Other factors also contribute to migration, not least the existence of a network of compatriots who can help with work, accommodation and companionship.
There have traditionally been large numbers of Poles living in the UK, so it has been a natural destination for Poles looking for employment.
By contrast though, Ireland, which previously had few Polish residents, has also seen large numbers of Poles arriving in recent years because of its boom economy's insatiable appetite for foreign labour.
By: N. Peter Kramer
