Butterley Company correspondence file on protective fencing around machinery On the fencing of conveyors following the death of Wilfred Harrison at Ollerton Colliery, Mar-May 1938, and fencing of machinery, including reports on visits to Butterley Ironworks and individual collieries, Oct 1944-Feb 1945. Also including loose plans (3) for safety improvement to face conveyor and gearhead equipment at Denby Hall Colliery 1938-1945