T. H. P. Dennis
of Chelmsford, manufacturers of horticultural buildings and related heating plant.
Imported generators and arc lamps from the Belgian electrical inventor Gramme, to light some ironworks in Derbyshire that were owned by some of Crompton's relatives. Crompton soon began to make his own arc lamps that improved on Gramme's designs and to develop a new type of dynamo.
1878 Crompton took over T. H. P. Dennis and Co's Chelmsford premises to form Crompton and Co, which soon became the country's leading distributor and manufacturer of electricity generating and lighting systems.