The right wing have been sending troops and tanks and other kinds of hired thugs out to keep miners in their place and force them to accept pay and work conditions that were often illegal for a long time. Generally with the benefit of hindsight, the miners were in the right.

So its probably ahistorical to suggest that Margaret Thatcher, only attacked the unions because they went too far. Maybe she just wanted to keep the money for herself and her political connections rather than pay the people risking their lives to mine it a fair wage.