Interesting to also note that the Union Flag/Jack is not the official flag of the UK, it's has just come to represent it by its widespread use in the Navy. So now by default everyone regards it as the flag of the UK and England as it was a regular sight on any British warship, and British warships were everywhere at one point. England has it's own national flag separate to the Union Flag. The only law that was decreed was that non British navy ships could not display any flag or pennant regularly used by the navy, which included the "Jack".
Just to be brutally technical the Union Jack only represents the nations of England, Scotland and the whole of Ireland. Northern Ireland and Wales have no representation on that flag. They are the crosses of St George, a 3rd century Roman Emperor's guard, St Patrick, a 5th century Roman/Irish missionary and St Andrew, a 1st century apostle and fisherman in Judea. Absolutely none of them had anything whatsoever to do with the nation of Australia by the way.
Wales was annexed before national flags were a thing, however the Tudor coat of arms had a set of Welsh Dragons added to signify the event. Unfortunately we all know the Tudor line was discontinued so that link was severed.
Interesting to see the Ryanair lyre shaped lady is very close to the lyre symbol the Protectorate under Cromwell used on their short lived flag, due to the association with the Kingdom of Ireland (the harp flag). So Ryanair is flying both the Irish national flag, next to the rego, and a representation of the old Kingdom of Ireland flag on the tail.