I've been learning 'The Hackler from Grouse Hall'

Its a very interesting song with references to Coercion, Parnell, Balfour etc., placing it sometime in the 1880's (whether it was written then, or later is another matter). The placenames are all around Co. Cavan which, by the way is a very interesting, scenic and under-rated area.

I always thought from the context of the song that a hackler might be a poitín maker or moonshiner. The manufacturers of this beverage seem to think so too. http://www.thedrinkshop.com/products/nlpdetail.php?prodid=2095
Any thoughts?