Obverse: CONSTANTINVS PF AVG Reverse: COMITI AVGGNN 24mm, 4.95g, 6h. RIC VI London 167 . Photo courtesy of CNG and reproduced here in accordance with their conditions of use.
This coin caught my eye in a recent CNG sale because of the placing of the shield. On the helmeted types of Constantine at London the shields are more typically placed at the left shoulder rather than in this more forward position. After I received the coin, I was examining it with a colleague who suggested that the shield was decorated with the head of Medusa.
On closer examination this appears to be the case as can be seen from the detailed photograph. I would be interested in hearing of any other London mint shields with similar decoration.