Hilda is not BBC only. She appeared in "The Mating Season". Madeline visited her to help her through a streak of broken heart. Hilda had temporarily ended her engagement, because the man had dared to hog a tennis match when they played a mixed double together. It was really dramatical. She also promised Bertie to plead his case with Madeline, because she seems not too impressed with Gussie.
However, yay for lesbian Wodehouse women, but Madeline just hurts my mind. Since reading this my brain screams soppy poetry about alabaster breasts at me.