The 60-page report by the National Institute of Economic and Social Research (NIESR) says that Britain is unlikely to be the preferred destination for Bulgarians and Romanians when labour restrictions are lifted.
And those who do plan to come are unlikely to take advantage of the UK's social security system, it adds in a direct rebuttal of arguments put forward by the UK Prime Minister.
On 25 March, Cameron said that net migration to the UK needed to come down radically “from hundreds of thousands a year to just tens of thousands," and promised new controls to rein in migrant's access to healthcare, housing and benefits.
"What we have is a free National Health Service not a free International Health Service," Cameron said.
The Prime Minister’s speech was delivered against the background of a campaign in the tabloid press warning that hordes of Bulgarians and Romanians would flock to the British Isles when labour restrictions are lifted on 1 January 2014.
Bulgaria and Romania have denounced the campaign and the European Commission has said that there was no evidence whatsoever of ‘social tourism’ within the EU.
The NIESR report was commissioned to provide Downing Street with evidence to assess the potential impact of migrants from Bulgaria and Romania. However, it makes plain that the UK will not be their favoured destination with Spain, Italy and Germany more attractive to them.
Romanians and Bulgarians have been free to travel to the UK without visas since 2007, the report stresses. The UK’s doors therefore are already open to themand no dramatic changes in migration flows are foreseen.
More than 100,000 Bulgarians and Romanians already live in the UK but they have been largely confined to jobs where there are labour shortages, such as hospitality, cleaning, and construction.
These existing migrants may stay in these jobs after 2014 or find work which is currently closed to them, the NIESR report says. They may also move elsewhere within the EU once restrictions are lifted across the EU in 2014.
The authors also stress that those who do come to the UK should not be treated as social benefit "tourists". Most are in fact likely to be young and without families, at least initially, and so their impact on public services is likely to be modest, the report says.
The Guardian newspaper quotes Sir Andrew Green, of Migration Watch UK, as criticing the NIESR report for “failing to estimate the likely scale of migration after next year's changes,” calling it a "bucket of whitewash".
Keith Vaz, chairman of the home affairs committee in the British Parliament, said estimates of the expected changes on migration were lacking and demanded the government commission a full study into the impact of the move.