Okay, so I didn’t take anyone’s suggestion. But I’m going to award the prize to kizmet_42, whose nomination of “The Green Lion” for its alchemical resonance led me to my choice:
The Crow’s Head.
Which is a) alchemical, b) pub-like, c) suitable to the Onyx Court, and d) a reference to the supposed burial of Bran the Blessed’s head in London.
kizmet_42, send your address to marie dot brennan at gmail dot com, and I’ll send you your prize.