Just in order to make clear the extent of Hamish Imlach's claims, here are the sleevenotes from his 'Scottish Sabbath' LP (1976):

"Die Melodie dieses Liedes stammt aus Hessen. Hessische Söldner in der britischen Armee hatten sie mitgebracht. In Schottland wurde es eine bekannte Dudelsack- und Geigenmelodie. Mein Urgroßvater, der Reverend John Imlach, machte einen Text dazu. (Ja, ich habe einen presbyterianischen Pastor als Vorfahren!)"
(The tune is originally from Hessia, brought over by Hessian mercenaries in the British army. In Scotland it became a popular tune for the fiddle and the pipes. My great-grandfather wrote a set of lyrics for it. (Yes, among my ancestors there is a Presbyterian pastor!))

I suppose that these are the lyrics Hamish used to sing. They go:

THE GAUDIE (translated as 'the salmon')

Chorus:
Oh gin I were where the Gaudie rins
Where the Gaudie rins, Gaudie rins
Gin I were where the Gaudie rins
At the foot o' Bennachie

I never had but twa richt lads
Dearly loved me
The tane was killed at the Lowrin' Fair
T' other was drooned in the Dee

Had they geen my love e'en man for man
Or yet a man tae three
But they crooded in so thick on him
He couldnae fecht or flee

He gie'd tae me the Holland fine
Our wedding dress tae be
I gie'd tae him the linen fine
His winding sheet tae be

The collection 'Songs of Scotland I' also states, "Written by John Imlah from Aberdeenshire, for some years tuner and traveller for Messrs. Broadwood & Sons. Published two volumes of poems and songs." I found this 19th-century (I believe) collection in the German Folk Song Archive at Freiburg some years ago. Unfortunately, due to a major refurbishment at the time I was thrown out before I could note down author and year, and compare the lyrics. I've been planning to go back ever since ...