Where does London start and end? Do you live in the heart of London, or just on the edge?
Some say you're in London if you're within the M25, others say London ends at Zone 2. These arbitrary lines are too simple.
James Darling's Londometer uses data and maths to create a much more complicated arbitrary percentage
Or try some example locations: Buckingham Palace, Bank of England, Notting Hill, Crystal Palace, Edinburgh Castle. Or view the heatmap.