Fellow Histarchers:
Thank you for your responses on- and off-list to my query about the
maker's mark (see below). I have been assured by the amateur
archaeologist who found the piece (a 9.5 inch diameter 'hotel ware'
plate) that it is Gd. P. Co., and not G.C.P. Co., so we are still at a
loss. If we come up with a solution, I will post it.
 
Jim Gibb
The Lost Towns of Anne Arundel Project
Annapolis, MD  USA
 
Gd. P. Co.
 Porcelain
[?]LASGLO[?]
 [three wing-dings]
 Warranted
M [encircled)
 CHINA