@BadFridays, you don't appear to have fully comprehended that Horizon had no idea who the driver was unless the Keeper blabbed it it to them, inadvertently or otherwise! If the Keeper simply referred to the driver in the third person, then that is not a problem. However, if they gave away the "golden ticket" advantage by throwing away their PoFA 2012 defence, they have, figuratively speaking, blow both feet off with a single shot!
Whilst there may be some defence in the fact that there is a validated permit that allows parking beyond the limits on the day, this has been much much harder to deal with than if the Keeper had simply appealed without identifying the driver, as there is no legal obligation of the Keeper to do so to an unregulated private parking company.
A simple appeal on the lines of: "I am the Keeper. I refer you to the answer given in
Arkell v Pressdram (1971)" would have been sufficient to get your POPLA code and have the assessor tell Horizon to cancel the PCN.