Mr Mustard thinks that answer is wrong, for two reasons
- the council can only impose restrictions on the public highway (save for one anomaly which is they could issue a PCN for parking other than on the carriageway if the public highways borders private land to which the public have access, which isn't the case hear).
- there is the risk of double jeopardy with the private parking company also still able to issue Parking Charge Notices for breaches of their signage.
What do you think, dear reader? Mr Mustard has been wrong before.
This case in the key cases section of the London Tribunals website, would suggest Mr Mustard is wrong (although the answer isn't logical).