Help with identifying age of Dewars?

My uncle was given a bottle from a friend and we believe it to be rather old bottle of Dewars. Its a smooth round bottle about 12" tall. Cream colored, metallic seal on top, with black lettering, but no label on the bottle itself. Seal reads from top, looking down at bottle John Dewars and Sons Ltd distillers Perth all in a circle, distillers in middle. On side of seal it reads Awarded 50 Medals with, again, John Dewars and Sons Ltd Perth on one side and on the opposite side of the seal, it has some sort of Royal seal, and reads below the seal, By Appointment. ON the bottom of the bottle there are two initials: N B. Otherwise it is a smooth, round bottle, with about a 4" neck that is sort of fluted.

It was found under the garage of a house on the national register in California, near Sacramento. We know nothing else of the origination of the bottle.