"To answer your question about casting billy... no, I don't think there was."
You don't think there was....what? You don't think there was ONE person in all of American and British musical theater who could have acted the role of Billy as well as Hayden and sung it far better? I think Brian d'Arcy James could certainly have done so, without question, and therefore it's quite ironic that he was only in the CHORUS of the LCT production of CAROUSEL.
Of course, it's conceivable that those who cast the show were unaware of Brian when they were first auditioning people to play the role in England, and I have no idea exactly when they became aware of Patrick Wilson, James Barbour, and Marcus Lovett. But my point still stands that there must have been other options in casting that role.