OP, you posted:
I requested evidence that signage was present on the day in which the alleged contravention occurred. No such evidence was provided and the photo you have obtained was taken on a different date.
Are you saying that the signs are at the location where you entered the CPZ? If so, the fact that they have taken them on a different day is to their credit, isn't it, because this means they have given drivers ample notice. Let's be clear, an adjudicator would find on the balance of probabilities that because they were there on or about 4 May then they were there on 14 May. The burden of showing they were not would fall to you IMO.