As immigration has become a hot topic in the UK, here are some key claims and some facts drawn from the Organisation for Economic Co-operation and Development, the UK Labour Force Survey, and the London School of Economics' Centre for Economic Performance. Compiled by The Scotsman.
CLAIM: Immigration into Britain has risen.
True. There were about 60,000 economic migrants a year in the early 1980s, and there are now about 150,000 a year. Immigrants were 7 per cent of the UK workforce in 1984 - that had risen to 10.5 per cent last year.
CLAIM: Britain has a particularly high rate of immigration.
False. About 8.5 per cent of the UK population was born abroad. In Germany, the figure is 12.5 per cent; in France, 10 per cent; and in the Netherlands, 10.1 per cent.
CLAIM: Immigrants are from poor countries.
False. Last year, the top five "sender" countries, who provided some 30 per cent of all immigrants to the UK, were India, South Africa, Poland, the United States and Australia.
CLAIM: Immigrants tend to be low-skilled.
Mixed. Fully 20 per cent of immigrants in 2004 had degrees, compared with 17 per cent of the UK-born population. But 19 per cent of immigrants had no qualifications, compared with 15 per cent of UK-born workers.
CLAIM: Immigration is an economic "problem".
Probably not. Most economists argue that immigration is sign of a healthy economy creating jobs and attracting migrants. And since immigrants are, on average, younger than UK-born people, they do not contribute to Britain's pensions crisis.
CLAIM: Immigrants place a burden on Britain's public services.
Reliable data on the use of services are hard to come by. One solid figure is that 27 per cent of health professionals in the UK were born abroad, suggesting that the NHS at least benefits from immigration.
CLAIM: Immigration is an important issue all across the UK.
Actually, immigrants are not evenly spread across the UK. South-east England draws almost half of all immigrants, despite making up barely 20 per cent of the UK population. Scotland attracts a disproportionately small number of immigrants, and needs more to offset a fast-falling population.
CLAIM: There are thousands of illegal immigrants at large in Britain.
True, but no one knows the exact number. The government refuses to give an estimate, although one leaked Home Office document suggested up to 500,000. Migrationwatch UK, an anti-immigration think-tank, estimates 250,000.