Obviously, there's not going to be a second vote, and as I've said on these boards before, I think it would descend into brutal unpleasantness. And a 'Remain' result would not be a forgone conclusion by a long shot
But if there were to be, how could a Remain campaign avoid being patronising, alienating and be more effective than 'Project Fear'?
I think it would have to focus on a very local basis on what an area does get from the EU, ie emphasise the positive, and point out the total lack of solid improvements that Leavers can point to in return. 'Exciting opportunities' don't count. Maybe pointing out the ways that Brexit will not solve the problems that people are complaining about, and suggesting ways that the government could, for example, address unemployment, lack of housing and so on, that would do much more good than leaving the EU.
Like I said, purely hypothetical, but I do think the Remain side suffered from snobbery, a patronising attitude and an inability to listen to genuine concerns and suggest alternatives.