1981- planned de-industrialisation, a planned move to a service based, finance based economy. Leeds was always in better shape to handle that due to the Building Societies based there (which all became banks and were taken over by multinational banks). Manchester, I think has always had a much wealthier "hinterland" , that as the road network has developed has allowed it to become a huge hub for the area.
I think our "Marxist" council is getting a bit of a hard time here to be honest. Meadowhall (and the whole of the Don Valley development) is hardly an exercise in Marxist economics. I'm not saying we have a great council but I'm not sure it's at the root of our slow economic progress.
BTW - over the last 20 years to council, labour have been in control for only 11 years, so we hardly fit a loony left label
Love the coasters