The gold shield was sent out blank to be engraved with the owner's initials.
I have seen a lot of guns with them left blank. Maybe they didn't care or did not want to do anything to hurt the resale value by personalizing it.
At the top of the page, it says:
"Not all Parkers will exactly meet these descriptions because Parker would alter a gun to meet a customers requirements if possible. Parker shotguns are custom guns and descriptions found here are those of their most common features."
So if yours is not just like the pictures, that may mean the original owner ordered it that way.
And if it is not in such good shape, too bad, but somebody paying $400 for a gun in those days was probably going to use it.