“She played it all over, she even composed ‘Songbird’ from the album Rumours on this piano.” McVie used the piano on the road again in 1982 when Fleetwood Mac toured behind Mirage.

But one viewer that night, it turned out, had the ear of Clive Davis, the music-industry rainmaker. The viewer insisted that “Songbird” was sure to be a hit, and Mr. Davis agreed.