They took the simple and lazy way out, as I feared.
The PCN is flawed because it omits a date. A non-mandatory element cannot replace a mandatory one, IMO at all but certainly without an explanation. This is not a guessing game where the keeper is required to join up dots.
The Traffic Signs Regs state:
Where the bay is reserved for an individual disabled badge holder, an alphanumeric identifier, with or without the word “ONLY” may be added after “DISABLED”.
But when so reserved, the upright traffic sign must include the alphanumeric identifier, otherwise the road marking and sign would conflict.
Contrary to their assertion, an upright traffic sign may include the word "ONLY".
It makes you wonder whether there is a TMO in this case and what it provides.