The North Middlesex Gas Co. Ltd was formed as a non-statutory company in 1862. It became statutory by Parliamentary Order in 1871 and gained further powers via the 1895 Act. The company came under the control of the South Eastern Gas Corporation in 1937. The company's works were situated in Mill Hill on Bittacy Hill and their area of supply covered Finchley, Hendon, Mill Hill and a part of Golders Green.
On nationalisation in 1949 the company vested in the NTGB