Reference | Title | Date |
RHP146000 | National Coal Board Inspectorate plans of workings | 1957- |
RHP146000/171 | Plans of workings at Ordnance Survey National Grid Reference NS 26/5418 Knockterra Colliery, Garrallan A Mine, Changue, Humeston, Garrallan, Crofthead, Knockterra noted on these plans. | 1958-1964 |