This week marks the 55th year since a coal tip collapsed above the village of Aberfan, killing a school full of children and their teachers.

A shadow fell that day, and I know that there are families in our communities who suffered a terrible loss, and for whom that shadow has never fully lifted.

Our thoughts will be with all of those families this week, as they mark this horrible milestone.

No criminal proceedings were ever brought in the wake of that disaster, and nobody even lost their job.

But another bitter injustice has stalked our valleys in the years since: namely, that other coal tips still litter our mountainsides.

Almost 300 of these tips are classed as being “high risk”, with 70 being in Caerphilly, 59 in Merthyr, and 16 in Blaenau Gwent.

And an ugly row has erupted recently over who will pay to make these tips safe. I find this frankly astonishing, and am dismayed that the Conservatives in Westminster have passed the buck to the Welsh Government – an institution that didn’t even exist when the coal was extracted and the tips first appeared on our mountains.

This task is one that should have been carried out by Westminster decades ago – it is they who should foot this bill of betrayal.

Coal used to be known as black gold.

It’s an arresting image: since it was, after all, a commodity that brought untold wealth to communities outside our valleys.

But the wealth was pulled out of the ground and taken away from Wales: we were left with the dust, the filth, and later, the catastrophe.

And since the landslip in Tylorstown last year, I know that many communities who lie in the shadow of coal tips have become desperate for the slurry and filth to be removed, once and for all.

Wales should not have to pay to clear up the mess and the horror left behind by the coal industry.

It should fall to Westminster to do this – and it’s about time they admitted it.