The second consulship of Constantine and Licinius (COS II) began on the first of January AD 312 and this coin, struck to commemorate it, was originally described by Mionnet and later repeated by Cohen (#397): “P. M. TR. P. COS. II. P. P. Femme assise sur une double corne d’abondance, tenant un bâton de le main droite; dans le champ, un astre, a l’exergue PLN. (1065; de J.C. 312.) Mionnet P. B. 30 frs.”
Maurice included the coin in “Numismatique Constantinienne” (1908-12) but it was later omitted from RIC presumably because of the incomplete description and doubts as to its existence.
In the 1980s Pierre Strauss rediscovered this coin in the Musée de la Moeda de Lisbonne (“Museum of Money”) and describes it as follows: Ob. CONSTANTINVS P F AVG Laureate and cuirassed bust right. Rev. P.M.TR.C-OS.II.P.P. Young person, diademned, sitting left on two entwined cornucopiae. Cloak over left shoulder, horn full of fruits in left arm, right hand raised holding a sceptre. In the exergue PLN, star in the left field. 4.00g. (inventory no. 2952).
A unique coin and a very rare dated type for Constantine that firmly links the star in left field issue to AD 312 but probably raises questions as to when the issue started and how long did it last. One could argue that this dated coin was likely to have been produced in late AD 311 to commemorate the start of the consulship. Other coins of this issue produced to commemorate the victory at the Milvian Bridge (28th October 312) and the return of Rome suggest that it continued towards the end of AD 312. Added to this we have the weight reduction that takes place during this issue. Huvelin includes this coin and discusses the dating of the star in left field and the star in right field issues in her article in Numismatische Zeitschrift.
Huvelin, H. "Les deux émissions londoniennes", Numismatische Zeitschrift 1990, p.29-50 pl.VI-XV.
Strauss, P. “Un Nouveau Nummus de Constantin 1st Frappé à Londres”, Mélanges de Numismatique in honour of Pierre Bastien, Wetteren 1987, pp. 181-185, pl.13. (see images above).