According to his website, Alex Prior has taken up the cello, and is “keen to reach the level needed to play Elgar’s concerto” (the photo of him with a cello looks like it’s a few years old, so he may be on to Shostakovich by now). He already is a much-performed composer, pianist, French horn player, mandolinist, and growing celebrity. He’s been written up many times in print, and Alex Ross and Elaine Fine, who brought him to my attention, recently blogged him.
Oh, and he sings a bit. Two years ago, when he was 12: