David Cameron’s proposals on free movement recognise that the European Union is very different now from what it used to be. When it was essentially a club of rich Western European nations, total freedom of movement was workable. But now that it includes countries whose GDP per head is less than half ours it is not.

This is not a particularly Eurosceptic insight. As I reported back in February, Nick Clegg and the Liberal Democrats were thinking of basing future transition controls on per capita GDP to prevent an unsustainable level of immigration.

But what is true is that unless the freedom of movement issue is dealt with, it’ll be hard for any government to win a referendum to stay in. Nigel Farage already says that the out campaign he’d run would be mainly based around immigration. He’ll argue that without leaving the EU, this country won’t be able to stop huge numbers of people moving here every year.

The question is, though, how much can Cameron get out of any future renegotiation on this. I suspect that given concerns in other northern European countries about the issue, he’ll be able to get freedom of movement limited to freedom of workers and others who can support themselves. Whether this will be enough to reassure the public remains to be seen.

Tags: Bulgaria, Immigration, migration, Nick Clegg, Nigel Farage, Romania, UKIP