Central City
From Tardis Wiki, the free Doctor Who reference
Central City was the capital city of Earth that existed by the 28th century. It encompassed the whole lower half of England, including London. (TV: "Strangers in Space") By the 30th century, the Seventh Doctor explained that it was "Spaceport Five Overcity," which used to be known as "Central City," and before that as "London." (PROSE: Original Sin)
In the third quarter of 3950, Mavic Chen was elected as Guardian of the Solar System in Central City. (AUDIO: Neverland) The Space Security Service had its headquarters there. (TV: The Daleks' Master Plan)
According to one account, rather than being in England, Central City was located in New Washington. (PROSE: Mission to the Unknown)