I’m hoping we have some Sondheim geeks here, a not unreasonable expectation.
After my daughter and I saw the Tim Burton version, I checked out the Lansbury/Hearn PBS performance from the library. And she was sitting here watching it, and she wanted to know, “What’s the deal with this weird-looking guy they’ve got playing Toby? It’s a man, not a boy.”
And I told her all about how there are child labor issues with working with children in show business (and she said, “What about Les Miz?” and I said, “They generally rotate teams of kids in and out as the run goes on”), and about how it’s a grueling part (on stage, at least, where you can’t rest in between takes), and about how it’s challenging music to sing in the first place, so maybe it’s hard to find a 12-year-old boy who’s capable of carrying the part.
And of course, that having a grown man who is a skillful actor can add depth to the part that having a blank-faced, inexperienced boy doesn’t (she had to admit that the gifted singer in Tim Burton’s version was rather wooden–“Yeah, his face was all, like, nothing…”)
So all in all, it’s obviously just easier to work with a vertically-challenged grownup tenor who has the professional experience to be able to handle the part of Toby.
So then I wondered if it was customary to do that for stage versions of Sweeney Todd, or what. It seems to me (although I haven’t sat down and studied the score) that Toby’s two big numbers are perhaps the most straight “melodic” of the work, tailored for the singing skills of a child, and with more note “cues” given by the orchestra (“here’s your starting note/sing along with this phrase”), so possibly Sondheim was anticipating that at some point, an actual kid would be called on to sing them?