I wonder what would happen if you brought your own beer - a good quality one, or literally one of your own? Would they charge you "cappage"? And would it be a [i:2rp6gn9m]tenner+[/i:2rp6gn9m]??
I was in Kahn's Balti House in Donnybrook about 2 years ago and they had a BYOB-friendly policy, with reasonable corkage. I had wine with me, so I don't know if beer drinkers (and there were many) were charged, or how much.