...young Peter Wingfield could totally have done Howl. He can smarm, he can do disarmingly frank cowardice (this is kind of Methos' whole shtick), he has a knack for having the sexual tensions with a brick wall. He probably would have wound up causing Howl/Calcifer to become the breakout ship of the hypothetical fandom, actually, now that I think of it. As long as Calcifer wasn't voiced by Miracle Max like in the Disney dub, which presumably he would not be. (Christian Bale makes a surprisingly convincing Ghibli Howl in that dub, I don't recall if you've seen it, but of course that's not quite the same thing as bookverse Howl.)