Wedding Ring Hallmark H.A and o or 0 at End

by Jenny
(uk)

Hi, I'm researching my grandmother's old wedding rings and I was wondering if anyone could help me with information on the hallmark. I've worked out the carat (9), Purity (375), assay office - Birmingham (anchor) and date - T (1943) but I'm not sure what the o or 0 'mark at the very end is all about.

I'm also interested in the makers mark. I've found H.A in silver marks referring to the Atkin Brothers in Sheffield but I'm not sure if the gold maker's marks are different (it seems a bit strange to have a Sheffield makers mark with the ring assayed in Birmingham). Any help would be really gratefully received. Thanks