Historically, moving people and goods by water has been much faster than by land, which leads to a bit of a paradox: coastal areas of island nations tend to be very cosmopolitan, while more remote areas can be very insular.
The Brexit vote will probably reflect that fact. I expect the Greater London area to go heavily for Remain and the hinterlands for Leave. For an American, this sounds a great deal like the familiar red state/blue state dichotomy, and some of the arguments made by the proponents of Leave could come from the mouth of Donald Trump.
The UK, the US, and the world all have plenty riding on the outcome of today’s vote. I will post my reactions tomorrow.