Can anyone tell me the name of the colliery at SN 526 106, SW of Tumble?. Seems to have been of fair size & working ca 1950's but escaped Mike Gill's maps, the Colliery Guardian maps etc. The nearest place names are Cwm & Pen-llwyn-gwyddau.
nearby Nant-ddu colliery which seems to have closed by 1918 but is also shown as working again on 1981 OS map.