Not paying when I'm not in the wrong.?? Not for the cited contravention perhaps, but parking on the footway .....!
Anyway, putting this to one side:
The prohibition is statutory(see link below to the Traffic Management Act)hence why signs are not required: holders of driving licences are expected to know.
85Prohibition of double parking etc.
(1)In a special enforcement area a vehicle must not be parked on the
carriageway in such a way that no part of the vehicle is within 50 centimetres of the edge of the carriageway.
An Act to make provision for and in connection with the designation of traffic officers and their duties; to make provision in relation to the management of road networks; to make new provision for...
Are you the keeper and are your DVLA details current?