Well, I initially thought it was from the Glasgow Pottery Works (mid 19th century), however it does not quite have all the elements required to identify it as such. Most potter's marks, especially using the royal crest, has the company listed underneath the banners which normally contain the motto of the family, region or company (in Latin).
I have a few other ideas and will hopefully find you an answer. With regard to region, did you discover this piece in the US or in Europe? If you could, and don't mind, give me a specific town or a radius of a town, I could narrow my research considerably. Thanks!
L. A. Wolff