Mostly an Irish instrument until post Chieftains times when everybody and his dog went Celtic - then they all went local making their own of it and calling it what ever they liked.

A good place to begin is at the Chiff and Fipple website where the local flavors are available and boasted about ... endlessly.

In fact that site even has the audacity to imply that Oirish TW is a mere subset of TW proper and OC we all know that such a claim is rubbish.