Perryman, you are of course right.

You only have to look at Switzerland to see that. Although outside the EU as a member of the EEA they currently accept freedom of movement for EU citizens.

If the UK voted to leave I am pretty sure we would end up in a similar position of having to accept things like freedom of movement (but maybe with quotas) in return for unimpeded access to EU markets.

Immigration can't be removed from the economic reality that people have always migrated to where the jobs are and for economies to grow you sometimes need those migrants.

At the same time in any negotiation you are more likely to get a better deal if the other party knows you are willing to walk away. In other words if you are not willing to vote to leave you will get nada/rien/gar nichts from our European cousins.