Confidence: I'm as sure as I can be.
Notes: The white spot on the hindwing, visible in front of the white band confirms this species is not P aurata. However, separation of P purpuralis from P ostrinalis requires inspection of the underside to get a certain identification. In purpuralis the white sub terminal white line is straight and peters out before reaching the costa (leading edge) whereas in ostrinalis it curves round to meet the white post-median band at the costa.
P purpuralis is the commoner species but because of the similarity of the species and resultant misidentification, ostrinalis' distribution is not well known.
P. ostrinalis has a narrower forewing and paler yellow markings but these characters are not diagnostic.