Britain in particular in this regard has the problem of real centralization; every build-up, every investment pretty much goes to Greater London, while the smaller towns around e.g. Birmingham and such tend to slowly die off. Germany effectively has two rust belts that it supports highly differently - the Ruhr area and East Germany; the East is in structural decline with ongoing emigration for the past 25 years, while the Ruhr doesn't see that but remains stable.
Structurally really economically challenged areas in the European Union are different. South Spain with its 10 million people - Andalucia has 35%+ unemployment rates! - for example never had industry, and while some recent developments (property bubble bursting) pushed them further down they've been in that state since WW2 pretty much. South Italy is much the same.