Heraldic banner of arms. The Plantagenet kings of England used the blazon "gules, three lions passant guardant in pale or armed and langued azure" (red with three walking lions with blue claws and tongues one atop the other) and the design has been associated with the kingdom ever since.
This banner has a ratio of 4:5.
Own work based on: Royal Arms of England.svg by Sodacan
This file was derived from: Royal Arms of England.svg by Sodacan