The way I see it, a lot of free market conservatives were pro-stay, and a lot of trade unionists and classical liberals were pro-leave.
Seems to be along pretty blurry lines to me.
Ultimately if you chose to live in your bubble, you will see what you want to see though. Good luck.
You are completely correct. Immigration alone was never enough to win. Most of the Tory MPs agitating against the EU were because of sovereignty issues (see people like Hannan, Carswell, Boris, Gove, Redwood etc) And as you correctly pointed out plenty of trade unionists (and the top two in the labour party) were for leave.