The glassblowers.

According to www.fantasticfiction.com/p/mervyn-peake/glassblowers.htm, "First edition of poems Mervyn Peake wrote when, in his words, he was "commissioned as a war-artist to record my impressions of work in a glass-blowing factory near Birmingham, I found on entering the huge, ruinous, grimy, wharf-walled buildings a world upon its own, a place of roaring fires and monstrous shadows.""