Incorrect signage?

The more I tell, the more hopeless it gets! No, the driver was not attending the club. It was due to an engine issue and the driver was unable to stop nearby, so used the car park. I tried my best to convince the club as I'm sure it will upset more people in the long run.
But anyway, I now realise it's too late to get the 'mugs discount', so may as well go for POPLA.

Thanks for everyones help so far. I will give an update, but also summarise and add more information which may paint a clearer picture;

I received the PCN as the RK. I was not the driver.
The Parking Eye notice showed vehicle entering/leaving the car park via ANPR camera.
The car park is a social club and signage indicates that members and visitors should input their registration number into a terminal in the club house.
The young driver used the car park because the check engine light came on in the vehicle and they were worried something serious may happen. There was no convenient parking available on the nearby street. They then went off on foot for about 1 hour to seek asssistance, later removing the car when they had been reassured that it wasn't that critical. (In fact the driver didn't know the car had been to the garage previously, which had just reset the light and told me to let them know if it caused more trouble). Later, I even explained to and asked the garage if they would provide a receipt as evidence, but they refused because the job was done at no charge!
In a slightly distressed state the driver didn't spot or acknowledge the signs. (In any case, I'm not sure if there would have been an opportunity to register the car, as the club was not open until 30 minutes after the driver first parked). I did appeal to the club initially, giving the circumstances, but they refused to get the PCN cancelled as the driver is not a member.

However, I am a bit reluctant to pursue this to the bitter end as I understand that POPLA aren't interested in 'extenuating circumstances' as described above. The car park has had new signs put up all around (see previous pictures) and I feel it may be unlikely that PE can be successfully challenged on this relatively new installation. As stated before, I don't know if there is any mileage in landowner permission/chain of authority, there is nothing on the land registry to indicate who that is.

So basically it comes to this; I have, as RK, 14 days to cough up £60, much to my utter disgust, or I ask for a POPLA code to contest it. I'm not confident on the evidence I have that I would win the appeal and then the cost would go up to £100. Much that I admire people who go all the way, I don't relish the considerable time and hassle required to defend myself should it come to court action with PE.

As ever, I am grateful for your comments.

Thanks for the responses, which I do appreciate.
Should I reluctantly fork out the £60, or appeal with POPLA?
If I lose the POPLA apppeal, I presume I will then have to pay £100, or embark on the lengthy process that could lead to court action (which I don't want to do).
I feel that unless anyone can give me reasonable hope of winning the POPLA appeal with the evidence I have outlined, I am inclined to pay the £60 to make it go away.