I've no idea where / when I learned it, maybe from the singing of Dominic Behan, but the town sounded like Bellamoray, and the nyahs can be sounded through the nose while the nose itself is pinched shut and one beats carefully on the throat (just below the adam's apple if one has one) giving a very warpipes sound.
The tune's in general is very like 'Strawberry Fair' - "singing singing buttercups and daisies", except that in the third line there is a descending line from high doh -
doh, lah soh, fah me fah me doh lowlah. Fourth line is lowsoh doh, me, ray doh, ray me, doh.
Chorus repeats lines 3 and 4.

Hope that helps

Ewan