Who's she talkin' about? Old queen who?

Mrs. Louisa Wilberforce:
...May I ask you where you studied? One-Round:
...Well, I didn't really study any place, Lady... I just sort of... picked it up. Mrs. Louisa Wilberforce:
You know, I was so surprised when I heard what you were playing. It brought back something that, really, I'd completely forgotten all about: my 21st birthday party. You see, my father had engaged a string quintet to come in and play in the evening; and while they were playing Boccherini, someone came in and said the old queen had passed away. And everyone went home. And that was the end of my party, all that time ago, in Pangbourne. [Silence] Mrs. Louisa Wilberforce:
Well, if you'll excuse me, I'll run and make the tea. The kettle *must* be nearly on the boil. [She leaves] One-Round:
Who's she talkin' about? Old queen who?