The following bronze coin of Emperor Valens has Securitas Republicae as reverse legend. It was struck in Constantinople. The exergue reads CONSP plus officina letter which is likely to be Delta. I just wanted to know if this officina is published for that series.
Sorry, I cant answer your question, Calbrey In the meantime I show the same coin,but from the Siscia mint and bump up your question
Here is the listing in RIC ix, p. 216 for your coin. The obverse legend on your coin is 2b: And there is no star in the field at left ... So yours is RIC 21c1. That officina letter is probably A because the mintmark CONSPΔ isn't described in RIC for this issue.