Large Plate - Silver Plated

I received a large plain plate (approx. 42 cm diameter) that appears to be plated in silver. The only markings appear on the back near the centre of the plate that read:
G C
I B
Each of these letters are approximately 12 mm in height. Please see attached image.

This plate was passed down through my family and is believed to have come from Scotland. My Scottish ancestors came from the Queenslie/Roughazie area of Glasgow and the nearby Parish of Cambusnethan (i.e. Wishaw).

An antique dealer in Canada has suggested that one set of initials could be the owner while the second set of initials may identify the maker.

I would appreciate any guidance in identifying the markings and possible age of this plate.

Regards,

David
Silver Plate001.jpg