Also known as the BBC or more affectionately, the Beeb. Founded as the British Broadcasting Company on 18 October 1922 to do test radio transmissions from Marconi House in the Strand. On 14 November that year the first BBC radio transmission was from station 2LO, at Marconi House, from which it had been sending test transmissions since 11 May. That year John Reith was appointed as general manager. The Company became the British Broadcasting Corporation on 1 January 1927. Television transmissions began from Alexandra Palace in 1936.
2022: Diamond Geezer has a good summary of the main London addresses that Auntie has used over the last 100 years.