Hi Jo - a crown on gold plus the karat (spelled with a "c" in Britain, abbreviated "c" or "ct") was used from 1798 until 1975 in Britain. An anchor is the symbol for the BIRMINGHAM assay office in Britain.
Sometimes you find pictorial marks on jewelry resembling UK marks but they are not British hallmarks. Some costume jewelry have a crown or anchor or both in their trademark, or company mark. These are called "pseudo-marks" and without the benefit of a photo it is impossible to tell the difference.
The numbers may be registry marks or manufacturing marks of some description.
The large stones in the brooch that you describe, could be precious gemstones, paste, glass, etc but again without the benefit of a photo it's impossible to tell. Please provide more information and attach a photo in a follow-up submission if this is possible.
Thank you for writing in from the beautiful apple isle...
