The national/regional hatred seemed to increase after Thatcherism then possibly even accelerate after Blair. Maybe it was always there and I never noticed as much, or was too young to notice. Read a few good articles about it in the papers recently, with de-industrialisation and Thatcherism, the rise of globalization, rise of London, centralization, collapse of the Scottish Conservative Party vote, early introduction of the Poll Tax in Scotland, loss of heavy industry, rise of financial and social inequality all being stated as reasons.
If you watched and supported England, on the TV in a bar in Scotland in '96 and again in 2000 it became very apparent how things were moving.
But I think there's more to it than all that, and again think we are finished as a United Kingdom if we move onwards on our present trajectory.
The rest of the world seem bemused or amazed by it all.