There are the council photos:





While there is no evidence showing where the sign was in relation to your vehicle, we know as a fact that there is only one bay with no other sign. Any signs in other bays are irrelevant, so the question is then whether it was reasonable for your to believe you were not parked in the loading bay, and the standard is that of the notional diligent motorist who knows and complies with the traffic signs regulations.
None of your photos show anything resembling a bay divider line, and the Traffic Signs Manual explains at Chapter 3 that:
13.6.8. Where two bay markings, associated with different conditions, are sited next to each other there should normally be a gap of about 100 mm between them.
Would you be able to go back and get some close-up photos of what you say looked like a bay divider? The photos you've got are all taken from too far away. I have also requested the traffic order for this bay, but it will take several weeks to get it back.