I don't know if this is the right sub to put this in, but why is there no Welsh characteristics on the union Jack?
The Union Jack was first created as a national flag in 1606 to symbolize the united kingdoms of England and Scotland (united at this point in the personal union of England, Scotland and Ireland under James I/VI -- not formally united as kingdoms yet). Wales was in 1606 a part of England (having been so since 1284) so it was "represented" in the flag with the English Cross of St. George. After the Acts of Union of 1800 formally united Ireland with Great Britain, forming the United Kingdom, the diagonal cross of St. Patrick was added, to form the present-day flag.
I wrote about the weird rules of heraldry that created an asymmetrical flag in this older thread -- it's quite possible to fly the Union Jack upside-down!