I found Tannahill's version in this thread. Other than the additional verses about the "lads o' the South" and "though simple are the joys," and where the choruses fall (after each four lines instead of eight) this is the same.

The tune I have is unlike either tune in the database, or that of Wild Mountain Thyme. I don't know if it's the same as the tune commonly associated with the Tannahill version of not.