For London population statistics covering the past 2000 years, see the Historical Overview of London Population article. Also relevant is the Defining London article.
Because of the conflicting definitions of London and Greater London, the population of London varies accordingly. The fact of the matter is that South East England becomes more and more densely populated the closer you get to central London. Wherever you draw the boundary there will be urban areas split by the boundary.
The "official" London population - the London administrative area of thirty-two London boroughs and the City of London - was 7,517,700 as of mid 2005.
However this does not take into account the whole of the London metropolitan area and hence this figure should not be used for comparisons with other world cities.
The Office for National Statistics recorded a population figure of 8,278,251 in its 2001 census but this included parts of the continuous built-up area falling outside the London administrative boundary.
Wider definitions of the metropolitan area sometimes coincide with definitions of the southeastern part of England (a geographical area whose own definition can vary considerably). One such definition describes this area as covering 6,267 square miles (16,043 km˛) and holding a population of 13,945,000 in 2001 – larger than the combined populations of Scotland, Wales and Northern Ireland.
Sometimes much more broad definitions are used. Demographia records a population of nearly 14 million for London's metropolitan area. The Greater London Authority has a broader definition still, defining the "metropolitan region" centred on London with a population of 18 million, covering large parts of South East England and part of the East of England administrative regions.