You didn't see the entry signs - or saw them and didn't know what they meant. Despite it being only last Saturday, you first couldn't recall how you got your car in that position but now you can categorically say 'that this isn't the direction I initially entered the RPZ from'?
Because I know the way that I came into Hertford and which way I first drove down Bull Plain. I also know how the car got into that position, which was because I turned around before parking, obviously. I just can't recall for sure whether I passed the zone ends sign and went back past the entry sign before parking. I don't believe I've contradicted myself in anything I've said. And yes, either way I would have passed the entry sign at the other end either way, presuming it's still there and wasn't obstructed.
You get two bites at the council before an appeal so why not send at least a challenge on the signage not being clear enough but it does seem as though you concede you didn't know about RPZs.
Yes, I think I will do that. Is not knowing about RPZs a concession? In my opinion they can't expect every driver to know the intricacies of every parking regulation.
Have a look at the RPZ section in this to see if you can spot any guidance the council hasn't followed:
https://assets.publishing.service.gov.uk/media/5c78f895e5274a0ebfec719b/traffic-signs-manual-chapter-03.pdf
Firstly, regarding the entry sign which I must have passed, it literally couldn't be any closer to a no entry sign to an adjoining street. So that's 15.2.3 contravened by the council. It's not even 100% clear that the RPZ is not in the one way road which is no entry from that direction.
Secondly, there are disabled bays within the RPZ and the council also appears to be letting disabled drivers park outside of the bays. But neither is stated on the entry sign...
"Where there is some provision of on‑street parking or loading within the
zone, this is indicated on the lower panel of the entry sign"
With regards to 15.3.1, "signs within the zone indicating the prohibition of waiting... are prescribed...". Prescribed presumably meaning mandatory.
It continues... "The aim should be to place signs strategically so that where drivers might be tempted to stop,
they can see a sign". They have clearly failed to do that in my opinion because no repeater sign is visible from where I parked.
So yes, I will try challenging it on these grounds and also send them a URL for a photo with a view from where my car was actually parked which if they do not bother looking at, will apparently invalidate the PCN alone.