Possible Clues:

• Note held by Puccini but not Vivaldi and Purcell but not Britten?
• Piano student's reference point
• It's almost at the centre of a piano keyboard
• Reference note for a certain sitter
• Note whose key is (almost) central on a piano keyboard
• Note what Anglicanism has to offer?
• 'Home' key for a beginning piano student
• Note bourgeois girl going missing
• Its frequency is about 262 hertz
• Reference key on the piano