In reply to Postmanpat:
you are right on this point, Pat. but in this issue, sentiment matters as much as objective reality, on both sides. a contributory factor to the leave vote was the perception that immigration was out of control, and that leaving meant 'taking back control'
but- over 50% of immigration was from non-EU countries, and already under our complete control. i would speculate than for many people, it was this immigration that was of particular concern, but of course i have no actual evidence for that. the impact of the notorious Farage 'Breaking Point' poster would give some support though.
anyway; it seems to me that many people are likely to have voted leave believing that it will solve a 'problem' that was already completely within the government's power to deal with, and which it was choosing not to.
likewise, there are many contributors here who fear what the future holds for them as EU citizens already living here, or fear for their ability to recruit more to come. now, i'm sure some deal will be reached that doesn't involve mass deportations and that there will be a skilled migrant policy allowing people to come in future.
but people only have one life; and while it is uncertain what that will be, they will take stock of their situation and many will- and are- choosing to move elsewhere, or not to come in the first place. i have also had conversations with trainees in my field, who are going to look elsewhere for senior positions. the perceived 'tone' or attitude towards non-british nationals is important too- even if this is just a perception, that's how people work, we aren't robots following opportunity-maximising algorithms.
so when there is no clarity on arrangements, but a likelihood that these will involve at best a lot of form filling, and a mood that is unwelcoming, and a perception that the economy is likely to do less well, many people will indeed decide to explore options elsewhere.
and if enough people do that, then the perception becomes the reality- it will hit the 'bottom line', tax receipts- just as the perception that we'd control immigration, in a way that we could actually already do, hit the bottom line in the referendum, ie votes.
a bit rambly, but in a rush and dont have time to edit...!