Many thanks.
Following your comments I have searched the forum and see that the notice doesn't comply with Paragraphs 9(2)(e) and 9(2)(h) of the Act. Is the following appeal sufficient at this stage, or should I be more specific?
I am the registered keeper of the above vehicle.
I challenge this Parking Charge Notice.
The Notice to Keeper does not comply with the mandatory requirements of Schedule 4 of the Protection of Freedoms Act 2012. Accordingly, you cannot transfer liability for the parking charge from the unknown driver to the registered keeper.
I am under no obligation to identify the driver and decline to do so.
Therefore, please cancel this Parking Charge.