Can Helena Bonham Carter sing? According to Variety, she'll be doing her own singing when she plays Mrs. Lovett in Tim Burton's film version of Sweeney Todd. I suppose Broadway buffs will be upset at the news, though personally I'm just relieved that Patti LuPone wasn't cast (she's been doing that part in what seems like every recent concert performance and revival, and she still seems terribly miscast to me).
Both of the lead parts in Sweeney Todd are sort of strange in terms of vocal writing, because they're parts of near-operatic length and difficulty but were cast with decidedly non-operatic voices, Len Cariou and Angela Lansbury. Part of the decline of Cariou's career after Sweeney, it was speculated, had something to do with the strain of singing a part that really needed a heftier voice; his voice couldn't handle it and he was never quite the same again. Lansbury got through it better, because while she's not a trained singer, she has the ability to switch to a soprano-ish head voice when the music gets high, and because her part wasn't quite as big or as exhausting as Sweeney. Still, the original choice for the part was an actress who also had a trained soprano voice (but could also belt) -- Patricia Routledge -- and it would be nice to hear the part cast with that kind of singer, just as it would be especially nice to hear Sweeney cast with a big baritone voice of the kind Broadway had in abundance in the '40s and '50s. That's not going to happen in Burton's version, of course, since he's made the decision to cast actors he works with regularly (Depp, Carter) even if they happen not to be singers.