The Flag of the States of Jersey
Originally the island of Jersey was using a plain red saltire as its national flag.
A long time before its adoption by the Order of St Patrick, and its subsequent use within the Union Jack of the United Kingdom. Its use in Jersey is hidden somewhat in history. One claim is that the FitzGerald family included it as part of their coat of arms, and owned land in Ireland, as well as in Jersey.
Another line is that the flag comes from Normandy. Except that there is very little proof to back up this claim.
A third theory is that during the early wars between England and France, the Channel Islands where granted neutrality by the Pope, and where allowed to trade with both sides. In order to differentiate themselves form the English, and thus preventing attack by the French, Jersey took the English red cross, and rotated it 45 degrees to create a saltire.
Once the Channel Islands formally fell under the British Crown (but not the British Government, apart from ultimate governance issues), the use of the Union Jack grew, and slowly replaced the Jersey Saltire.
However, the Channel Islands where the only part of the United Kingdoms territory that fell under Nazi Germany occupation. Use of all British imagery was banned, though the island got to keep using its heraldic symbols. The Nazi Swastika flag was flown over the government offices.
During the occupation, the Jersey Saltire grew in use once again, and in the later half of the 20th century, a debate grew up about the flag. One one side, people wanted to keep it as it had been in use by the island for over 300 years, on the other side of the argument, people who wanted to update the flag.
The reasoning behind this desire was that the flag itself was regularly mistaken to represent Northern Ireland, or for one of the international maritime flags in use for signalling. One major idea was to use a banner that used the islands three leopards.
However, a compromise was reached which saw a modified arms of Jersey surmounted with the Plantagenet crown being placed in the upper quadrant in the centre of the flag.
The flag was adopted in 1979, proclaimed by the Queen in 1980, and first flown in 1981.