I was just musing about Corbyn's point, when asked about limits to immigration, who said that free movement contradicts that. This seems obvious - as soon as you set a limit, you do not have free movement.
But historically, this is fascinating, since the right have traditionally advocated market economics, (which includes movement of capital, people, goods and services), and the left have criticized it. But now in the EU debate you seem to have the reverse, the right-wing are recommending state control of immigration, and the left arguing against it, (even though it may lower wages).
Of course, there are other arguments against free movement, for example, Farage's idea that I would not like to live next to Romanians, or whoever. And this argument seems to be heard on the campaign trail - there are too many of 'them' here.
But I think that in classical economics, migration is a response to labour shortages. I think Rhiannon mentioned the potato farmer who desperately needs pickers, and East Europeans turn up to do it. I'm not sure how the state is supposed to interfere with that, but it poses the interesting spectacle of a right-wing government controlling the economy in certain ways.