London is currently divided into 33 widely differing boroughs (13 of them in central London), which are run by local councils with significant autonomy. Two traditional 'cities', Westminster and the City of London, technically make up London. The 'one square mile' (about 2.7 sq km) of the City of London at the heart of the conurbation is known simply as 'the City'. Boroughs are subdivided into districts, which generally tally with the first group of letters and numbers of the postcode.

Districts and postcodes often appear on street signs and are quoted when giving directions; this is vital since names are fre­quently duplicated or cross through a number of different districts. To further confuse visitors, many streets change name (Holland Park Ave becomes Notting Hill Gate, which turns into Bayswater Rd before becoming Oxford St) or duck and weave like the country lanes they once were. Street numbering can also be bewildering: in big streets the numbers on opposite sides can be way out of kilter - 315 might be opposite 520 - or go up one side and down the other.