The coal-mining spoil tip in Aberbargeod was once 400 feet high, a disaster waiting to happen, until the tragedy at Aberfan in 1966 (when 144 people, mostly children in the town’s primary school, were killed by the local spoil tip sliding down the valley) caused an urgent re-evaluation of the dangers of these tips. Aberbargoed’s was reduced in size, walkways and culverts were built around it, trees have been planted on it, and it’s now a wondrous place for biodiversity.

It is, however, still a steep huffing-puffing walk to the top on a hot summer’s day, particularly when, as I did yesterday, you walk straight up, instead of using one of the longer zigzagging paths. But it was worth every drop of sweat I exuded as, not only are the panoramic views superb, but Aberbargoed tip is also home to a colony of Grayling butterflies.

Graylings prefer dry, well-drained locations with sparse vegetation, so a spoil tip is the perfect spot for them. And, as they like to hunker down with the bright eye spots on their forewings well hidden, the mottled colouring on their hind wings means they’re incredibly well camouflaged on the stone chippings.

I was lucky, though, that a couple of the Graylings I spotted yesterday seemed curious about this stranger who had invaded their territories. So, I plonked myself down on a slope next to a path and waited. And sure enough, first one, then a second butterfly came to investigate. If it hadn’t been as hot as hell, I could’ve stayed there for hours.

You can read more about the environmental importance of preserving the spoil tip sites on Liam Old’s excellent website, Colliery Spoil Biodiversity Initiative.