The graph here is interesting in that regard: http://www.bbc.co.uk/news/uk-england-15445418 http://www.bbc.co.uk/news/uk-england-15445418 The manpower dropped

The graph here is interesting in that regard: http://www.bbc.co.uk/news/uk-england-15445418 http://www.bbc.co.uk/news/uk-england-15445418 The manpower dropped steadily until 1970, when the numbers failed to drop further. Presumably Thatcher 'unblocked' the unionization that prevented the continuation of this steady decline between 74-80