There's fault on both sides here, yours and the council's, so if it got to adjudication based upon what is known and how it's been presented to date in your initial reps then IMO the outcome would not be open and shut.
You parked; you knew you were within a marked parking place and yet you did not look diligently for an applicable traffic sign but instead apparently looked across the road where a parking place had a Mon-Fri restriction and guessed/hoped/wished this applied to where you were parked.
Your initial reps included the following:
..on a 50m stretch of road there are 4 signs and 3 are mon-sat 10-4pm and one is Mon-fri 10-4pm (it was this one that I looked at as it was clearly visible 2 metres away from my car, albeit on the other side of the road. All signs in this area were mon-fri 10-4pm about 1-2 years ago, then changes started to occur. The street where this occurred is a small connecting road between two residential streets, I felt it was reasonable to assume all parking bays were consistent with each other.....??
'There are 4 signs' So why did you consult one which, as the holder of a driving licence, you are presumed to know did not apply to where you were parked? And when did the knowledge of 4 signs i.e. 3 within your bay, come to your attention? Your whole defence is based upon the invisibility of a sign, but if you have acknowledged knowing it was there before you parked, where does this leave your defence? I'm simply looking at what you've already submitted.
From the council's perspective, the CEO's traffic sign photo shows the one further from your car which implicitly accepts that the visibility of the nearer was compromised for their purposes, so why not for yours? And the fact it was the further as opposed to furthest is because there were only 2 in situ(not 3 as you stated in your reps) and GSV shows that a traffic sign had been displayed closer to your car in plain sight for some time and IMO as regards signs this should be your focus.
The third, middle, sign is a very recent addition because when the parking place was introduced in 2012 the council sited only 2 signs, one at either end. However, in 2020 the council decided to erect a third sign on a pre-existing column, paradoxically at a time when the overgrowth from the garden evergreen tree immediately behind - whose relentless march from within a garden to enveloping the footway can be seen in GSV - was guaranteed to obscure it. The sign behind your car has been in situ continuously since 2012 except for a short period in 2019, therefore the council, quite correctly, attach importance to its presence because it is the first one in the bay and alerts a driver to the restrictions. Its absence for a short period could perhaps be excused because there are 2 other signs, however, when the closer of these is itself obscured, in this case by a tree, this leaves only one sign potentially visible, nearly 40 metres away. The first sign was missing on the day...why has the council allowed this to be is a line of defence I would consider for formal reps hoping as a minimum to elicit a nonsense rejection which could swing an adjudicator to your side.
But there are some who would think: you parked; you failed to make any attempt to look for an applicable traffic sign; it's your fault.
