Not just the miners strike, but does anyone remember Jack Dash, communist leader of the London dock workers
? Famous for strikes, and a believer that the nation could not manage without his members.
The result was the closure of the traditional London docks, with trade transferred to modern, non union, container ports.
I am not sure you have demonstrated cause and effect here. The move to modern container ports was already happening and London did not have the space or transport links to make that work.