it’s to retain route knowledge via Cobham for Fratton drivers. Basically one of the morning 1G services runs via Woking instead of Cobham, so to ensure sufficient trips 1P32 now runs via Cobham.
Even still one might expect an early-morning down, or late-evening up, journey to do this. Woking is obviously an important interchange and it seems a bit odd to disrupt the off-peak pattern by leaving a gap in Woking provision at this time of day.
Will catch people out too, who are expecting a consistent pattern between the peaks. I suspect the on train and on-platform announcements will need to be very clear and emphasise the different calling pattern of this specific service.