What is the capital of England?

London, and it is the capital of England and the United Kingdom without ever having been formally designated either - there is no act making it so. It simply is, by the accumulated habit of Parliament, the courts and the monarchy all being there.

It is also not really one city. The City of London is a square mile with its own police force, its own Lord Mayor and a corporation older than Parliament, in which some votes are still cast by businesses rather than residents. Westminster, where the government sits, is a separate city entirely. What everyone calls London is 32 boroughs and that square mile, stitched together administratively only in 1965.

The Romans founded it around AD 47 at the first point upstream where the Thames could be bridged and still reached by seagoing ships - which is the entire explanation for the location. It was burned by Boudica about fourteen years later, abandoned in the fifth century, refounded by the Saxons slightly upstream, and has burned down or been bombed flat several times since. It was the largest city in the world from about 1831 to 1925.