The only version of Windmills that I know, is on the LP No Strings Attached by The McCalmans (RCA PL 25086), from 1971. Joe, the MIDI you posted gets an OK from me too, it agrees with what The McCalmans are singing. Wild guess: Could it be that Fred Holstein got the song from the McCalmans - directly or indirectly? Since the McCalmans tend to sing in harmony a lot, someone who learned it from them might have had to guess at the tune here and there.