The statistics are that many more EU nationals live in the UK than UK nationals living in the EU.
Yes, immigrants are welcome, but there could be circumstances when they cause problems for people other than the people they are benefitting. Eg a fruit farmer makes a packet out of hard working EU fruit pickers, while denying UK nationals a job. This may be "the way it is" and people have to be philosophical about it and accept it, but can we really expect those denied a job to vote for circumstances where they are denied a job because of foreign labour? Probably not.
Do you KNOW anything of the situation in the Scottish fruit picking sector, Spud?
Farmers have tried to recruit local workers - paying above the 'living wage', I may add - but they cannot get enough locals, and depend on migrant workers to both plant and harvest the crop, which contributes significantly to our economy.
The same situation applies in our vital tourism sector.
A UK 'one size fits all' immigration policy might benedit some areas of England; yet why should Scotland suffer at their expene?