Welsh Silver Plate goblet - maker ID sought (MJC or JMC?)

Hi,
Hoping someone can identify the manufacturer of a silver-plated goblet manufactured in Wales? (see photos)

It stands 130mm tall and approx. 55mm wide (rim slightly wider than the base) and weighs about 137g .
Stalk and base are sealed - possibly hollow?
There are impressed marks on the base - "SILVER PLATE ON COPPER", a monogram/logo depicting a stylised J (or I?) over a crown-like capital "M" both overlaid by a smaller "C", and "MADE IN WALES"






Over the years I've found other such goblets (and candelabra - all in the same style with a beaded border near the base) advertised on online auction sites etc. and auction-house catalogues
- none of which have identified the maker.
Any further information would be greatly appreciated
Thanks in advance

Hi

This mark belongs to Jack Muller - he was a family friend since I was small child (he and my uncle met during the war and remained firm friends until Jack's death); I believe he died in the late 1990s. He and his wife lived close to Caernafon where he made all manner of silverware and supplied Boots the chemist giftware range for many years. I have a range of goblets and a marvelous candelabra. I hope this helps - I'm not sure I have anything else of help but if you have a question or two please feel free to contact me via theisland@talktalk.net