Top floor of pub off market square -- find pentagram? in the guys workshop? There's a locked door up there, I've found no key to.
Perhaps it is in there that you are talking about?
Yes, that's the one; I'm afraid I don't recall how to gain access offhand. Mindreading the barman perhaps? I'm guessing now, though.
And your avatar needs a Santa hat.

Edit: I decided to not be so lazy and checked: the barchap is indeed the key (sigh, my inadvertent puns are as bad as my deliberate ones...)