Sirius smiled at the note -- Leila had already drawn his attention to the couple with her. He should stop by later, he thought, and offer to give her some stage training. Ron might turn interesting colors.
Fields of Gold was after his time, but he'd heard it in Muggle establishments, and trying to resolve the story of it had set it in his mind fairly quickly. He wasn't entirely sure that the man was supposed to be alive and around at the end -- there was that last "remember me". It was possible to turn that all sorts of ways, though, and when he looked at Hermione, with the love she had left and returned to, and the child she had taken as her own, it was easy to just make it contentment and a finding of home.
While he had picked out the tune, he had never charmed in the accompaniment for it, so he lightened his amp and prepared to go it alone.
"This is a request -- for a marvelous little girl and her parents of the heart."