Ahhhhh yes....the Public Market....great place! I can't say for sure but I'm guessing that the sign was done in the late '50s or early "60s by either Foley Sign, Messenger Sign or Corey Sign although it may have been done by one of the other few that were big "main stream" in the area at that time or one of their "Snappers". I remember that sign as is since I was a youngster. That period was a real "Hay-Day" so to speak for the sign industry and its tradesmen. Many sign artists of that period, while working in union shops also "Snapped" alot of side work and made a very good name for themselves. A couple of them are still around today...some still painting signs the old fashioned way, some retired and taking life easy. I'm sure that you gathered quite a nice collection of photos of signage while here. You certainly were in the right part of town for it.
Colin, It would have been nice to meet you while you were in town. I could have given you a bit of a tour through Seattle and shown you some of its finest vintage signage along with some of their history and interesting details. If you return, I'd enjoy meeting you.