This bust type (Y) is not listed for this obverse legend (1d). It should come after RIC VI London 225.
It's not listed in Huvelin's “Les Deux Emissions Londoniennes†either.
Constantine I
A.D. 310- 312
23mm 3.9gm
C-ONSTANTINVS P F AVG; laureate and cuirassed, holding spear forward and shield on left arm.
PRINCIPI IV-V-[E]NTVTIS; Prince standing facing head left, cloak hanging from left shoulder, right holding globe, left reversed spear; * in right field.
In ex. PLN
RIC VI London --