I don’t have an authoritative answer, but I think my guess will be close to the mark.
Many countries have, in addition to a flag, a coat of arms. The colors of one may not be the colors of the other. In addition, the colors on the shield of the coat may not be the same as those of the torse and mantling (the cloth ring on the helmet which sits above the shield and the fabric that hangs from it, behind the shield, on the full heraldic achievment).
Countries may also have associations that have different colors. For instance, the Union Jack is often considered the flag of the United Kingdom, but is not the flag of England, Scotland, Wales or Northern Ireland. There is a UK flag that mimics the Arms, being divided quarterly and having the major charge of each kingdom’s coat in each part.
The Union Jack is red, white, and blue, as these are the major colors of the flags based on St. George’s Cross (red cross on white), St. Andrew’s Cross (white saltire on blue) and St. Patrick’s Cross (red saltire on white). But these cross flags aren’t the national flags of the component kingdoms. The flag of England is 3 gold lions on red, so the national colors of England are red and gold, not the red, white, and blue of the Union. Scotland’s flag is also red and gold, being a griffin in a sort of border known as a tressure flory-counter flory, both red, on a gold field. I think the Irish flag is a gold harp on a purple field, though Northern Ireland probably has something of its own I can’t bring to mind (perhaps the Red Hand of Ulster–a red hand on a white shield).
I’m afraid I can’t recall what the colors are for the torse and mantling on the full achievements for England, Scotland, and Ireland.
As I said above, I don’t claim to know for certain this is what is being referred to in the OP. I am also almost certain to have made some mistake in a detail or two. But I think something like this is your answer.