The UK's flag was originally made for the Royal Navy, but later just became the national flag through popular use. It's the same with the National Anthem of the UK, it's just been adopted from tradition and treated as such.

I find this interesting as a lot of people in regards to Northern Ireland push a narrative that the flag is unofficial. It was designed and officially adopted for the Northern Ireland Parliament by the Ulster King of Arms, Sir Nevile Wilkinson, from the Coat of Arms, for the then Parliament of Northern Ireland which was formed in 1921 and dissolved in 1972. In this capacity, it was the official flag purely of the government.

HOWEVER, the Minister of Home Affairs permitted anyone to use it as a symbol just representing Northern Ireland itself. It became used in sport and is still used today.

In my opinion, this gives the Northern Ireland Ulster Banners as much legitimacy as the Union flag. The only people who object to the Ulster Banner being used generally object to Northern Ireland having a distinctive flag at all because they object to the existence of Northern Ireland.

Anyway thank you for reading my tangent.

God save The King.