read the lastest post on the parking prankster's blogspot about planning consent for parking signs,
it is something I have beaten PE on before so not an isolated example.
So, if you get a Court Claim than one of the documents you should ask for from the parking co
is the planning consent for the advertising display board.
Check with your local council as consent is needed for any sign big enough to be acceptable
under the CoP covering the signs that form contracts.
Generally the parking co's do not apply for PP and rely upon existing consent from the stores.
However, in the case when I beat PE, the car park had a separate address to the store
as a building was demolished to make way for it and no planning applied for so not only were the signs illegal,
the car park was separate and thus would have attracted business rates of its own.
I know that PE applied for PP and had to erect new signage as a resulot of my action so it is always worth checking.