I really love this ship AAAA
(but I couldn't find old art of them made by myself besides that ask from 2023, sorry anon :7; but If you remember how the art was you can describe it to me to refresh my memory and I'll search it better).
Talking about headcanons, I haven't gone into it too much, but I think Arthur and Gilbert became closer than ever in the 4th century.
The two countries were so close that Frederick II and his sister were considered to marry Princess Amelia of Great Britain and her brother, respectively. These marriages did not happen because an Austrian figure feared this alliance and caused discord between the two nations.
Despite this, the two remained somewhat close, and they were allies in the War of Austrian Succession and the Seven Years' War.