Thank you, Martin. Indeed it is in Partridge -- also rendered as 'shuler', which is even nearer: tho oddly enough I couldn't find this usage on google, which wouldn't believe I didn't mean something to do with "school".

But, even then, why is the spelling altered for the song; which, I repeat, alters it to a word defined only, in OED but nowhere else I could find, as "sieve-maker"?

Still a bit mystified; but less so, thanks to Martin's & Fergie's helpful suggestions.

~M~