In March 2022, according to GSV, there was a sign that says "Permit Parking Only". You've not shown us the dates or the back of the NtK so it is impossible to check whether the NtK fully complies with the requirements of PoFA in order to be able to hold the keeper liable for the charge.
From what we can see, the NtK is, loosely compliant with the requirements of PoFA, at least enough to rule out any chance of the IAS considering not so. However, if, as you claim, there was no signage that brought adequate notice to the driver of the sum charged for unauthorised parking and was not adequate to bring the charge to the notice of drivers who park vehicles on the relevant land, then you nay have a defence.
Can you get some photos of the signage at the location with an overview to show if the notices they claim are there are adequate in oder to bring to the notice of the driver, the sum charged for parking there? Also, what is the keeper or the drivers relationship to the person that went in to do their task"? Is that person or the driver or the keeper a resident/leaseholder of the property?
Have you tried Plan A, getting the landowner/leaseholder of there property to get the PCN cancelled? IF there is a lease for the property, what does it say about parking and rights of way? What does it say about requiring a permit? What the lease doesn't say about parking is equally important.
You need to understand that remaining in the vehicle with or without hazard lights and with or without the engine running for more than 5 minutes will be considered as having considered the signage and agreeing to the terms on the signage. In other words, the driver entered a contract by conduct with the PPC. However, if it can be shown that the vehicle was parked in order to load or unload goods or drop or pick up passengers or was stuck there due a vicissitude, that is not considered parking.
So, the dates on the NtK need to be shown. The back of the NtK needs to be seen. Can you get some photos of the location including any entrance signs and other signs at the location. Ideally, any photos should show the view from where the vehicle was parked/waiting in order to see if the signage was prominent and adequate enough to bring to the attention of the driver that there were terms that should have been adhered to in order to avoid paying a charge. How is a driver supposed to get a permit to park there?
