Potterne, Wiltshire

A downward glance

‘Isn’t that slag?’ The Resident Wise Woman’s mind was more on geology than the elegant but rather forbidding Early English Gothic Gothic architecture of St Mary’s church, Potterne. What caught her eye was the black material among the masonry lining the steps in the churchyard, a by-product of smelting (probably of iron, though one sometimes sees copper slag): a substance that is hard, irregular, dark, and durable.

It’s something we’d noticed before in a different form in the Gloucestershire town of Newnham on Severn, where there’s a house partly built of slag. There, the material, produced during copper smelting, had been poured into moulds while still liquid, so that it set in big rectangular blocks ideal for building. Here at Potterne, though, it’s simply made up of irregular lumps. It’s dark, and more forbidding in its way that the architecture of the church, but has found a useful function.

I don’t know where this slag came from – Wiltshire is not a place I particularly associate with historic ironworking (the Weald and the Forest of Dean were more the places for this kind of thing) although I have seen online references to Saxon-period smelting in the Ramsbury area and Westbury had an iron industry in the 19th century. I’d love to know more about the origin of this unusually located and unlooked-for slag.*

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* Thanks to a reader who has pointed out that the Seend ironworks was not far away: this is a likely source.