“This lack of grasp and staggering complacency meant Brit­ain was unprepared for such a mass wave of migration.
“Consequently real strain has been put on our housing and public service infrastructure, with council tax payers up and down the country footing the bill.”

The IPPR report highlighted the huge gulf between the reality and Government predictions that EU expansion in 2004 would lead to just tens of thousands coming to Britain. At least 765,690 came under the Worker Registration scheme.
The A8 countries  –  Poland, Czech Repu­blic, Est­onia, Hungary, Latvia, Lithuania, Slovakia and Slovenia – joined the EU four years ago. Bulgaria and Romania acceded in 2007.

The IPPR believes around half the estimated one million migrants have returned home, but 665,000 nationals from all 10 countries were living in the UK in the last quarter of 2007. That was an increase of 548,000 since the first quarter of 2004.

The figures returning also have to be estimates because the Govern­ment has no measures in place to count people leaving the UK.

At the end of last year, it estimated there were more than 900,000 Poles resident here. Around half were Polish nationals, making them the largest group of immigrants, and the rest were “Polish-born”, meaning some may have changed citizenship.

Last year, Poles were registered in every local authority in Britain.

The IPPR report said: “This migration is likely to prove to be one of the most concentrated voluntary migrations in the world today.”

It added: “Post-enlargement mig­rants have moved to a larger number of different areas of the UK than have any previous groups of migrants.”

The researchers estimate that 10 million people flew between the UK and the 10 Eastern European countries, in either direction, last year – a three-fold increase on pre-2004 figures. Last December alone, 385,000 flew between 22 British airports and 10 Polish cities.

Liberal Democrat home affairs spokesman Chris Huhne said: “Turnstile immigration represents new planning challenges to Britain’s public services. But a key first step must be reintroduction of exit checks, so we know who is actually here.”

The IPPR team looked at the Labour Force Survey, applications for a National Insurance number, and the Workers Registration Scheme – applicants are required to sign up as soon as they start a job in the UK.

It also studied the International Passenger Survey and questioned Poles who had returned home after working in the UK.

Researchers predicted that rapid economic development within the EU states would mean fewer people coming to Britain over the next few years.

“Four in 10 of the returned Polish migrants we surveyed think that better em­ployment prospects in Poland would encourage Poles living in the UK to return to Poland for good,” they added.

The pound’s devaluation in relation to the Polish currency will narrow the gap between potential earnings in Britain and Poland, while the pool of possible migrants is set to shrink due to lower birth rates in the mid-1980s.

The Government says it will gradually reduce the number of migrants from outside the EU as numbers moving within the union grow. But the IPPR concluded that its predicted downward trend “raises the spe­ctre of labour shortages and increased off-shoring of British businesses”.

It added: “It also has implications for how the UK designs immigration policies, particularly in terms of the balance between EU and non-EU inflows.”

Sir Andrew Green, chairman of Migrationwatch, which campaigns against mass immigration, said: “We should not fool ourselves that the tide of immigration has now turned. The report only deals with Eastern European immigration, which, at its peak, was only a third of foreign immigration.

“In future the real pressures will come from the rest of the world where the Government has powers to control the numbers but seems to be determined not to do so.”

Immigration Min­ister Liam Byrne said: “Britain has always welcomed those who work hard, pay taxes towards public services and play by the rules. Today’s report says Polish newcomers did all three in a big way.

“Even though half of Polish migrants have gone home, we have to make sure we factor in any wider impact on public services in our new immigration system.”