Should the UK gov pay for post-coal clean up?

Wales and coal have always gone hand in hand. For centuries, we were one of the biggest exporters of so called black gold anywhere on the planet, but that money rarely stayed in Wales. What did stay in Wales were the scars left behind, nowadays in the form of coal tips dotted around Wales, many of which are at risk of slipping. The Welsh government are calling on Westminster to pay to fix this.