If you consider the traditional areas of Labour support being the industrial heartlands of the past, like Manchester, Liverpool or Leeds, then their support wasn't for leave, but remain.
It was the rural constituencies that voted leave. It's not the case for every large northern town, but analysis of the vote clearly shows it wasn't northern towns and cities that decided the result but rural areas.
Russian financed advertisements on social media were heavily backed in the two weeks leading up to the referendum, and before that started the remain campaign was comfortably leading. The Leave vote won by a little over 650,000 votes, it was the first time in the campaign leave were in front, and since the vote, the choice to remain has consistently been higher than leave.
The government have suppressed the report into that Russian backed influence on the result.