OP, see 17(c) and Interpretation section of the order.
A 'parking place' is the entirety of the area, 'parking bays' are the separate parking areas.
17. The council shall place and maintain such equipment, signs, markings as are required to give effect to the provisions of this order..
......
17(c) requires the council to 'place and maintain in the vicinity of each parking place appropriate signs indicating the restrictions ....
There's no silver bullet which would cause them to concede but the argument goes that if they believe that the driver breached a provision of the order and that this supports them demanding a penalty then similarly you would say that it's their own failure to comply with their order which had brought this about i.e. if the sign 'in the vicinity of the parking place' AKA the noticeboard had stated that such parking rendered the driver liable to a penalty then they would not have parked as they did etc....