Watch List notes:

Crispus as Caesar (AD 317-326), AE Nummus (20.6 x 20.1 mm 3.04 g 7h), London mint, CRISPVS NOB CAES, laureate, cuirassed bust of Crispus right, rev. SOLI INVICTO COMITI, Sol standing left, S above star and P in fields, PLN in exergue (RIC 122; CT 8.10.010 (this coin)), about extremely fine..
Ex Toone collection.
Ex CNG 221 Lot 524.
Ex Pickering collection.

A rare mintmark and issue for London, while examples for Constantine are relatively common, those of Crispus and Constantine II are all rare. This coin is illustrated on the CT plate

(£80 - £100)