Great Britain

Great Britain was the largest of the British Isles. It was governed by the United Kingdom, which also comprised the province of Northern Ireland. It was first united as one nation in the 1707 Act of Union under Queen Anne. Its capital city was London, with Edinburgh and Cardiff serving as the regional capitals of Scotland and Wales respectively. People from Great Britain were variously self-identified as "English", "Scottish" or "Welsh" — although members of any of these identities were also more generally considered "British" internationally. The Doctor's long association with the country led him to often be identified as British, typically when he was visiting other parts of Earth. (DW: The Gunfighters, Doctor Who)

History
By the 21st century Britain was identified as one of the most obese nations of the galaxy (DW: Partners in Crime)

In the 29th century, due to solar flares, the United Kingdom abandoned Earth for a starship; this continued until at least the 33rd century. (DW: The Beast Below)

By the 50th century during the later Ice Ages Brittanicus Base was located here. (DW: The Ice Warriors)