The flag of the City of London is based on the flag of England, having a centred red St George's Cross on a white background, with the red sword in the upper hoist canton (the top left quarter). The sword is believed to represent the sword that beheaded Saint Paul who is the patron saint of the city. The sword always faces upwards, when the flag is held on its side as a banner, the sword would be printed to face hoist and would be located on the left as it is hanging down.
This flag does not represent Greater London (which does not have its own flag, aside from the flag of the former Greater London Council), only the historical City of London which covers approximately 1 square mile (2.6 km2). All references in this article relate to that city, not Greater London, unless specified.
The flag derives from the city's coat of arms with the sword symbolising the sword that beheaded Saint Paul who is the patron saint of the city. Saint Paul has featured as a symbol of the city since about the 13th century, however his full figure representation was rapidly replaced with just his symbolic representation of the sword. However some believe the sword is a dagger that commemorates the dagger of Sir William Walworth, former Lord Mayor of London, which killed Wat Tyler, leader of the Peasants' Revolt, in 1381.
Brave Walworth, knight, lord mayor, that slew
Rebellious Tyler in his alarmes; The king, therefore, did give him in lieu
The dagger to the city armes.
- Fourth year of Richard II. (1381), Fishmongers' Hall.
However this is believed to be a fable, with the sword on the arms being used several months before the killing of Wat Tyler (Tyler being stabbed in June, and the Arms being designed in April).
The earliest mention of the city's coat of arms was on 17 April 1381 when the old seal was deemed "ill-befitting the honour of the City" and a replacement commissioned by Walworth. Both Saint Paul and Saint Thomas Becket featured in the previous design and were carried over to the new one similar to the modern design.