GEB/RPM can be traced as GREMPB, i.e. "GReat EMPire Britain" with shape of the Saint Andrew's Cross with a flagpole, SOW/CRE is SCREW with half rotation around the letter O representing the screw, OAG/LFB is BFLAG i.e. "British FLAG" which is fluttering and pinned by screw "O" at its upper left.

Difference between “GREMP” and “GReat EMPire” is “eat ire”, which can be read as “eat Ireland”. Great empire is about to eat Ireland. This reflects the international situation at that time. So GREMPB must be "GReat EMPire Britain" and BFLAG must be  “British FLAG”.

Regarding O of SOW/CRE as screw is natural. But “B FLAG with screw O” is more complicated. It needs more evidence.

BFLAG can be traced as “LAG FB” also. Its course takes figure of “FB surrounded by LAG”. Now looking at OAG/LFB again carefully, we find FB in GAOL!