BT's origins date back to the founding in 1846 of the Electric Telegraph Company, the world's first public telegraph company, which developed a nationwide communications network. BT Group as it came to be started in 1912, when the General Post Office, a government department, took over the system of the National Telephone Company becoming the monopoly telecoms supplier in the United Kingdom. The Post Office Act of 1969 led to the GPO becoming a public corporation. The "British Telecom" brand was introduced in 1980, and became independent of the Post Office in 1981, officially trading under the name. British Telecommunications was privatised in 1984, becoming "British Telecommunications plc", with some 50 percent of its shares sold to investors. The Government sold its remaining stake in further share sales in 1991 and 1993. BT is a Royal Warrant holder of the British Royal Family and has a primary listing on the London Stock Exchange, a secondary listing on the New York Stock Exchange, and is a constituent of the FTSE 100 Index.