>Through discussing the vote with the other leavers I know, not once was immigration mentioned as a concern
You seem to be a bit obsessed with backing everything with data. Do you want me to make a survey for the people I've spoken to? I'm not trying to say "immigration is not the issue and I have proof!", I'm saying that immigration isn't the issue for everyone, and that there are people in the main HN - reading demographic (and more than just me and the 5 I know, although I'm sure you're going to ask for a citation) that A. Don't match the image in your head and B. Didn't vote the way they did as some kind of attempt to lock out immigrants.
Your suggestion that discussions can only be had by providing data is just not true. If I were trying to assert a claim large enough to need a sample size then sure, but I'm not.