Re the Aberdeen printing: James Chalmers were father and son so the company under that name extends from 1740 to 1810 (not to be confused with James Chalmers of Dundee who covered a similar period). I've seen a J. Chalmers & Co piece printed in 1800. The son died in 1810. On the cover of the chapbook is a very crude woodcut of Mussel-mou'd Charlie, a famous ballad seller in Aberdeen. His dates are 1676 to 1782. Looking at the typography and layout I'd guess c1790 to 1800.