Strange hallmarks on old gold ring

by Aubrey Simpson
(London, UK)

I am trying to work out what some hallmarks mean on a gold diamond ring that I found many years ago. I am fairly sure that one is 18 cr although the top of the 8 is missing. I assume this means 18 carat gold. There is also an F and a P with no box around them. But the strangest marks are two number fours which alternate with what looks like thin triangles or cones, i.e. cone 4 cone 4

I can't see any other marks. Any illumination would be helpful!