Creskol got it right, as usual. British-made, with ostrich-plumes of Wales symbol, probably W&R Smith backmark. Also, I agree with Fyrffytr1, it's from the 1810s into the 1830s.
By the way... and the time this brass 1-piece flatbutton button was manufactured, the term "Plated" in a backmark always meant silver plated. Gold plate was called gilt.
Although it might seem surprising that this early-1800s brass button was found in Denmark, at that time the British seem to have been "the Buttonmaker to the World." Comparatively very few backmarks from other countries during that time period have been found. For example, France was as large as Britain, with about the same population, and just as wealthy a nation as Britain. So you'd think that French-made brass flatbuttons would turn up as often as British ones... instead of being extremely rare by comparison.