I'm not sure you can characterise Scotland as Labour anymore. Largest party in the Scottish parliament are SNP, second largest Conservative, Labour are a measly third place.

As much as London is Labour supporting it's only a very small part of their supporter base, their traditional heartlands are Wales and the North of the UK, both of which overwhelmingly voted to leave.

I'm no defender of Cameron, but the Labour party in the UK have absolutely failed – both recently and during their last period in government – to engage with long-term problems of identity, especially in the north of England. A huge number of traditionally Labour-voting areas have opted to leave the EU, and the party have to bear some responsibility for that.