The flag of England is the national flag of England, a constituent country of the United Kingdom. It is derived from Saint George's Cross (heraldic blazon: Argent, a cross gules). The association of the red cross as an emblem of England can be traced back to the Late Middle Ages when it was gradually, increasingly, used alongside the Royal Banner. It became the only saint's flag permitted to be flown in public as part of the English Reformation and at a similar time became the pre-eminent maritime flag referred to as a white ensign. It was used as a component in the design of the Union Jack in 1606. It has been widely used since the 1990s, specifically at national sporting events, especially during the campaigns of England's national football teams. In 1188 Henry II of England and Philip II of France agreed to go on a crusade, and that Henry would use a white cross and Philip a red cross. Thirteenth-century authorities are unanimous on this reversal to the intuitive. There then follows a historiographical tradition claiming that Richard the Lionheart himself adopted the full red cross flag and the patron saint from the Republic of Genoa at some point during his crusade. This idea can be traced to the Victorian era, Perrin (1922) refers to it as a "common belief", and it is still popularly repeated today even though it cannot be substantiated. Prince Edward, Duke of Kent made a variation to this in a bilingual preface to a brochure made for the British Pavilion at Genoa Expo '92. The relevant passage read: The St. George's flag, a red cross on a white field, was adopted by England and the City of London in 1190 for their ships entering the Mediterranean to benefit from the protection of the Genoese fleet. The English Monarch paid an annual tribute to the Doge of Genoa for this privilege Red crosses seem to have been used as a distinguishing mark worn by English soldiers from the reign of Edward I (1270s), or perhaps slightly earlier, in the Battle of Evesham of 1265, using a red cross on their uniforms to distinguish themselves from the white crosses used by the rebel barons at the Battle of Lewes a year earlier.