Nick,
My version is a mishmash based on all the versions I've heard over the years but the searchers verse probably came direct from a broadside. Yes I'm sure Q is right that it was written for a shilling by a printer's hack.

Franklin was originally, as a young man, a landbased explorer in Canada and went through great deprivations on expeditions to the north. I have several contemporary books on these early expeditions and the later sea-based ones, and indeed some of the books written on the searches. I seem to remember he was also as a boy present at the Battle of Copenhagen.