United Kingdom
"And that the Union Flag shall be Azure, the Crosses Saltires of St. Andrew and St. Patrick Quarterly per Saltire, counterchanged Argent and Gules; the latter fimbriated of the Second, surmounted by the Cross of St. George of the Third, fimbriated as the Saltire."
The Union Flag comprises three crosses on a royal blue background: a red St George's cross a white St Andrew's saltire a red St Patrick's saltire.
Editor's note: A 5:3 proportion is used here for a flag to be flown on land. 2:1 would also be appropriate for one to be flown at sea. This is potentially a controversial choice, 2:1 is often quoted as the "official" proportions ... by non-official sources. The Flag Institute could have been a compelling alternate source, being the origin of a 2008 bill (not passed) to better formalise the flag in law. It specifies slightly different RGB approximations of the same Pantone colors, but proscribes the same 5:3 proportions for use on land.
