You are unfortunately mistaken.
Did you not notice the No Right Turn and also the restriction signs, which with no times, apply 24x7 ? The restriction applies to Weymouth Terrace beyond those signs, and also the rest of Dunloe Street where you drove into.
I'm afraid the signage here is against you, so other than a "technical" appeal, based on council mismanagement of the enforcement process, (this includes PCN content), the contravention appears to be made out.