Butterley Company correspondence file on mineral supports from Kirkby Colliery, and leased from the Duke of Portland, under the Great Northern Railway at Sutton-in-Ashfield and Kirkby-in-Ashfield Including copy of agreement, 30 Dec 1916, plan of minerals around Great Northern Railway, early 20th cent, and comparisons of proposals, 30 Nov 1914. Oct 1914-Dec 1916