Glen of Imaal Terriers were bred to hunt and to work and, like it or not, they also earned their owners money in the “sport” of dog fighting. This now does not appear on civilised curriculum vitae so you may not have realised this. People who were around then speak that the Glen was supreme and this heritage was not that long ago.
So are you prepared, or willing to learn, to effectively handle a possibly dog-aggressive animal? Glens do not back down when challenged by another dog so this means a huge responsibility as you will know how your Glen behaves but you won’t know how others do!!