The bourdon is a carillon’s foundation bell, struck rarely but felt structurally by every other bell in the tower. At 1,850mm and 2.6 tonnes it was the largest single pour in the foundry’s records, cast in a pit mould with the sand rammed in eighteen separate lifts to keep the wall thickness consistent through a casting this size.
Carillon bells are tuned to a stricter standard than ring bells — a carillon is a keyboard instrument, and every bell’s five partials must sit in true chromatic relation to its neighbours, not just be individually well-tuned. The bourdon anchors Millbrook University Chapel’s 48-bell instrument, installed in 2016.