I found it! The original 2 inch scrap of paper on which the Tarbh doodle was -- er ... doodled. I'm no artist (as proven here) but it's the first and only graphical representation of a Tarbh in existence, so it's meaningful to me.

*pleased look of happiness*

[Update - Since the start of the "Tarbh Challenge" run by  graveyardgreg, this guy has been seen a lot more around the place. Fate, huh?]