Butterley Company correspondence file on the valuation of minerals undertaken with regard to the Coal Act 1938 Including copies of reports written for a similar exercise undertaken by H. Eustace Mitton, 1917-1918, including Derbyshire and Nottinghamshire collieries report 30 Nov 1918, copies of valuations of minerals for Derbyshire and Nottinghamshire, Sep 1935, and printed statutory rules and orders of the Central Valuation Board, 1938, with booklet of illustrative examples of method of completing the forms of estimate of value for the Central Valuation Board, 1938 Dec 1935-Jan 1942