I have never come across this, but in theory if a PC told a driver that they could "park there" ..... THEY COULD!!Save as provided in Articles 13 to 21 no person shall, except upon the direction or
with the permission of a police officer in uniform, cause or permit any vehicle or a
vehicle of a specific class to wait on any restricted road during the restricted hours
as specified on the Plans.
It would obviously end up as an appeal against a PCN but the Parking manager would have to consider that this "exemption" applies.