Hi Rory,

Your link to the tune appears to be the same as the one I link to, just in a different book from 1854.

McPeake has slowed down the tune, but it is essentially the same (to my ear).

I know this gets into the murky space of copyright law, but if I took a song by Led Zeppelin and changed one word in the chorus and used a harmonic variation on the melody, would I get away with claiming authorship? Unlikely.