The problem for the UK after WWII was that it gradually lost its source of cheap raw materials and captive market as the Empire was gradually broken up.
I have also seen it suggested that because the higher echelons of our class system had a distaste for 'trade' the children of those who became wealthy through manufacturing and trade imbibed this 'distaste' as they were sent to Public School and Oxbridge and mixed with the class they were aspiring to join. So the drive to create wealth through industry became moribund.
Of course, we also spent much of the US aid money in endeavouring to hold onto the Empire, instead of investing it in industry and infrastructure as European countries did.
Our economic problems also stem from the abandonment of Keynesian informed economic policy in favour of the anti-state theories of Hayek and Friedman, the 'neoliberal' economic theories which still hold sway today. Thatcherism, and 'austerity from 2010, placed too much confidence in 'markets' and thought it right to destroy public services, which, in actual fact, made a significant contribution to GDP and growing equality.
I suspect that today Keynes would say what he said 70+ years ago. In a recession the government should spend, to keep money flowing around the economy and to maintain growth.