Nah, that's all we know about Queen Beruthiel. I have this idea that the King got so tired of cats everywhere that he just had to banish his wife, spies or not.
Oh, and as how to burn potatoes - you just forget them as they boil away, while you're posting replies to Tolkien threads! But I saved them, and the whole dinner was a success. Now I can either do this or try to study... maybe I'll do both.