Hello, here is my likely Alex Katsch mark compared to beaumolo's.
The heads with the lower mark maybe look more "feminine" and perhaps less stylised. I think the lettering could be "G.P." and wondered it could be a Russian or German abbreviation for the manufacturing material, for as shown by the adverts he had outlets in both of those countries? We know that in British silver plate there are lots of names and short forms that were used.
Fishless