No, that's what happened. Listen to it:
[Carl]: I, I love the colourful clothes she wears, and the way the sunlight plays upon her hair
[Brian]: I....hear the sound of a
[Carl]: Gentle word, on the wind that lifts her perfume on the air.
There's a switch between vocalists there. And similarly on the "Whennn, I look" on the second verse.
I'm sorry. I suppose you must be right. I had wondered why there was a bit of a break in those verses but I hadn't noticed it was Brian on the falsettos. That's strange but interesting!
Thanks also, c-man and Roger Ryan. I'd noticed that on "Live at the Roxy", someone else sings those falsettos, and Brian, I think, sings a lower harmony, down a third.
But now, this news is clearly a very important argument against Carl singing the alternate version, but I don't think it is conclusive (yet). The thing about certainty is that if one is certain, then it must be true, but if one is not, then as far as one knows it could be true or false. And it still sounds like Carl to me. I wish I was certain! There is enough error in the world, especially regarding this week in Britain.
But if Carl couldn't sing the actual note, well that's unlikely because he sang the note "a" a year before on "Girl don't tell me" which is only a semitone lower. So perhaps it was holding on the long "a#" that was the problem, or perhaps it was because it would have been too loud and/or strained in normal voice, and his falsetto wasn't good enough, or some other reason. But presumably before long he was singing it in concert. When did he first sing it, though?
But on the alternate version, in fact those falsettos do sound like Brian mostly. I didn't mention it before, except that I thought Brian might be on the lead too. Especially on "IT'S WEIRD how she comes in so strong" the falsetto sounds more like Brian, but the rest of the line is so like Carl. So maybe they're both there.
But I suppose it makes it more unlikely still that Carl sang the chorus of the alternate version, unless one argues that he is singing loudly there and so can get those high notes, or that perhaps it is Brian and Carl together.
Some time I might go through it all and see which bits sound more like Carl and which more like Brian.