Touché.
It's not available in Derry, that's for sure. Nor can it be found in any supermarkets. And my brother is regularly in Belfast and like I said, only it seen it once.
To cap it off, my da's family all live within 5-10 mins of the brewery and have only heard about it but never tried the stuff either.
Have enquired on their Facebook to see if they have a list of stockists anyway.