Make your mind up time...again!...
http://www.baronage.co.uk/2002c/stgeorge.html
From Wiki (and mentioned by the Hairy Bikers...who can the argue otherwise?)
"Genoan origin
Some historians believe that the St George's Cross was adopted from the flag of Genoa, which dates back to 1096. The Genoese flag was adopted from the personal flag of St. Ambrose, the Fourth Century Bishop of Milan who was a key figure in the development of Christianity in the West. St. Ambrose's cross had become a symbol of Milan, then the wider areas of Northern Italy. (Because it was a common symbol in the region, it was the flag of the Lombard League, a coalition of city states including both Milan and Genoa that opposed Frederick Barbarossa in the 12th and 13th Century.) Genoa's patron saint was St. George, and its vast trading fleet carried the association between the flag and the Saint across the ports of Europe and the Mediterranean Sea.
Prince Edward, Duke of Kent, supports this theory:
"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 Geonoese fleet. The English Monarch paid an annual tribute to the Doge of Genoa for this privilege."[3] "