Thanks for the suggestions, but no, it is not "The Day We Went to Rothesay-O."

Nor is it any of the "Ranzo / Reuben Ranzo" etc. group. It is not a sea shanty.

It is definitely a shore song. My impression: a London origin, maybe dockside, as in press gangs, but not a sea song. Probable origin by its sound is 19th century, but it could be a more recently composed song in that style.

I believe the spelling "Rumsay" is correct, but can't be sure.

To give you an idea of the tune (it isn't minor after all, just sounds that way):

(In C)

.G      .G   C         D      E    C

Rum - say ho,    rum - say ho.

That much of the sound and melody I am sure of. Bob