OK - If you can buy coal - for the sake of argument:
1) For £15 / tonne from Australia
2) For £12 / tonne from Poland
3) For £20 / tonne from UK
Where would you get your coal from?
Fact is coal could (and still can) be mined and shipped half way around the world cheaper than it could have been taken out of the UK mines because of outdated and uneconomic working practices.
So ---- Why keep an outdated and filthy industry that pollutes and contributes massively to Global Warming?
The UK was unprepared for the arrival of the global economy. The Unions fought to keep and enhance protectionist working practices whilst Japanese factories churned out motor vehicles with barely a human interaction and ships manned with "cheap" crews took all of the UK freight and inexpensive coal from overseas made our mines uneconomical to keep open.
Industrial evolution and global economics - not appreciating these issues is common amongst the socialist working class because of long standing beliefs that Britain is truly great. It was, not anymore though.