http://www.edinburghassayoffice.co.uk/downloads/Gold_Plated_Silver_Article_Guidance.pdf
With the information from the site above, I would guess your ring to be 18k white gold with a silver plate. Origin of the maker is also a question. I do agree also the the former caveman with the shield thought. Below is an sample of the link from above:
Other Marks
3.1
Other than the silver hallmark or a 925 stamp on underweight items, no other standalone gold fineness marks are permitted on gold plated silver articles, because
they are potentially confusing and misleading to UK consumers. It is not permitted additionally to mark the article 9k, 10k, 14k, 18k etc, nor can the article be marked
375, 416, 585, 750 etc. For the same reasons, ‘American’ style mixed marks are not permitted either, for example 925 1/20 14k. This is the same as it has always been for
gold plated and rolled gold articles under the Hallmarking Act 1973 in the UK.
3.2
A gold fineness mark (not hallmark) is allowed if it is immediately preceded or followed by the words ‘gold plated’. For example an article with a silver hallmark (or 925 stamp
on underweight articles) can be marked as follows ‘925 & 18ct gold plated’.