John Kay looks at the spectacular underestimates of immigration from Poland and the other new EU members. The basis of the estimates was research commissioned by the European Commission.
My view is that, while planning and estimating things like this is important for the government to be able to manage the country, they don't matter because the government shouldn't be managing the country in the first place. If 15,000 East European immigrants are OK for Britain, why aren't 600,000? The question isn't how many we're going to get, it's how many we want. The idea that we know just what is going to happen as a result of any policy is a dangerous illusion, and leads to overconfident intervention in things that are not government competencies.
And I really don't see the problem. There are three reasons for opposing immigration:
1) It's bad for the economy
2) There isn't room
3) Our culture will be swamped by foreigners
1) is tosh. The only possible harm would be if they all came and started claiming benefit. This is unlikely - Britain isn't an attractive place to come because of its benefits, it is attractive because of its jobs. And if it happens it is only necessary to restrict benefits.
2) is also tosh. Our population isn't growing organically, there's easily room for twice the current population, and a lot more young working people is just what we need.
3) is not a respectable argument, but I find it hard to honestly assert that it couldn't conceivably happen. The danger tends to be exaggerated, but it's not impossible that life in this country could be made much more unpleasant by the presence of a large immigrant community with an incompatible culture. But Poles? If there's a clash of cultures going on in Britain today or tomorrow (which I don't think is the case to any serious extent, but am prepared to consider for the sake of argument), then, to put it bluntly, the Poles are on our side.