Nigel - Gold and yellow are heraldically equivalent. Yellow is 'or' (Norman French from Latin aurum) but, unless you have a sculptered shield which can be painted with gold paint, it is depicted as yellow. They used yellow paint, not gold, on their shields in the Middle Ages. Similarly with heraldic white, which is 'argent'.

You corrctly remind us that the only heraldic emblem of Wales is the red dragon on a green and white field. So the appropriate colours for a future flag for the Former United Kingdom (FUK) would be red, white and green. And the Scottish unicorn supporting the shield in the royal coat of arms would be replaced by the Welsh dragon. Ditto for the Scottish lion rampant in the second quarter of the shield. But we shouldn't rush into a redesign just yet. Northern Ireland might well unite with Eire sooner or later, and then the Irish harp would have to go. To be replaced, I suppose, by the dragon. So the royal coat of arms would end up as some sort of combination of lion and dragon in red, white and green. Perhaps we could join lion and dragon together and make one of those weird heraldic beasts, such as a griffin. That would be fun! Who wants to go on top?

While we're about it, we must really re-think the royal motto. 'God and My Right'. It hasn't agreed with any Zeitgeist since the swinging 60s. What would be appropriate for the early 21st century? And the rest of it too. What's Latin for 'Buy now, pay later, own it never'?