As with all the 'PB' range it is derived from Phil Barker's pair of books Armies of the Macedonian and Punic Wars and Armies and Enemies of Imperial Rome. PBC standing for Phil Barker Cavalry. This figure corresponds with illustration 29 in AMPW.
There is a specific horse for this model but the mount shown here is the PBH 65-217 which is listed as two different horses in the 72/73 catalogue: PBH 65 Cavalry Horse and PBH 217 Roman Cavalry Horse 1st and 2nd Centuries AD. The code is stamped on the base in the usual way.
As per usual we have thick and thin versions of the spear, this one is a thicker type. The thin ones are very delicate and likely to be broken if you can find them - easily replaced though.
