National Coal Board File.
N.C.B. File South Western Division, Area No6 – International Exchange of Students visit 1961. The file contains detailed information and plans on the Marine Colliery Trepanner and the Abertillery New Mine (Cwmtillery Section) Midget Miner.
This file has about seventy pages of information on the Marine Colliery and Abertillery New Mine (Cwmtillery Section), with many pull-out maps and blue prints from 1961.