Centrica plc is a British multinational utility company with its headquarters in Windsor, Berkshire. Its principal activity is the supply of electricity and gas to businesses and consumers in the United Kingdom, the Republic of Ireland and North America. It is the largest supplier of gas to domestic customers in the UK, and one of the largest suppliers of electricity, operating under the trading names Scottish Gas in Scotland and British Gas in England and Wales. It owns Bord Gáis Energy in the Republic of Ireland. It is also active in the exploration and production of natural gas; electricity generation; and the provision of household services including plumbing. Centrica is listed on the London Stock Exchange and is a constituent of the FTSE 100 Index. The company has its historical origin in the Gas Light and Coke Company which incorporated in 1812. Over the next 137 years it grew by acquisition of other gas companies to become the primary supplier of gas to Greater London. In 1949, under the Gas Act 1948 the ownership of the company transefered to a government agency, North Thames Gas Board. The Gas Act 1986 sold the company to private investors as British Gas plc.