Papers of Sir Ambrose Fleming, including extensive sets of laboratory notebooks which include accounts of experiments on carbon filaments carried out by Fleming when he was adviser to the Edison and Swan Electric Light Company, of tests on electrical and photometric standards carried out in the Pender Laboratory at University College London, and of experiments on valves and other aspects of wireless telegraphy; notes of lectures attended by Fleming and notes for lectures given by Fleming; patent specifications and papers on litigation over them; newspaper cuttings and other compilations by Fleming; papers on awards and distinctions; biographical notes; and correspondence. 500 of the 521 volumes are printed works associated with the collection.

Records of the London Electric Supply Corporation Limited and successor London Electricity Board, comprising plans of Main Transmissions Networks in the London, Essex and Kent areas, 1937 - 1951; and photographs of Grove Road Sub-Station, 195-; Carnaby Sub-Station, 1952; Neckinger Sub-Station, 1958; Horseferry Road Central Bank, 1959; Barnes Substation, 1960; Beech Station 'B' Sub-Station, 1969; Cable Tunnel under Surrey Canal, 195-; and Horseferry Road and Grove Street, 1928.