Butterley Company correspondence file on re-organisation of the Colliery Offices and the industry in gerenal Relating to the reorganisation of the colliery offices, including on personnel changes, Nov 1938-Mar 1939, including loose plan of Ollerton office; then on the general industry re-organisation including copies of minutes and reports of the Midland Counties Colliery Owners' Association, Sep 1944-Nov 1945 Nov 1938-Nov 1945