W. E. Oakeley
William Edward Oakeley, landowner of the Tan-y-Bwlch estate on which the quarries stood, amalgamated the three previously separate Rhiwbryfdir workings into a single business, Oakeley Quarry, in the aftermath of the 1882-83 rockfalls — at the time, the largest underground slate mine in the world.
Mines operated
| Mine | Region | Years |
|---|---|---|
| Oakeley Quarry | Gwynedd | 1878–1972 |
Record created: 22 August 2026