It may be worth appealing, but not yet.
Hilariously, according to the Notice to Driver (NtD) that was left on the vehicle, it only says the reason for the PCN is that the vehicle was "parked correctly within the markings of bay or space".

UKPC are a pathetic little company of vexatious ex-clamper scammers. They have absolutely no idea of the drivers identity and their PCN does not comply with all the requirements of PoFA to be able to hold the Keeper liable. You do not appeal an NtD until day 27 after the issue. You only appeal as the Keeper. The Keeper is under no legal obligation to identify the driver to an unregulated private parking company.
By appealing on day 27, there is a good chance that they will respond and issue an appeal rejection without having ever issued a postal Notice to Keeper (NtK). Without knowing the drivers identity, they can only rely on PoFA to hold the keeper liable as long as the NtK is issued no earlier than 28 days after the alleged contravention and no later than 56 days after.
Even if all appeals fail, no one pays UJPC a penny of they follow the advice provided here.
Come back nearer to day 27 after the date of the PCN and we will provide a suitable appeal that the Keeper can send to UKPC.