In all cases, the parking
management contractor has paid for the installation of the camera
systems (we simply provide somewhere for the "control computer" with
electricity and an ADSL link back to their base). These systems can
cost several thousand pounds. In return, the contractor gets an
agreement which gives them the "absolute" right to enforce whatever
the rules are. I make sure there's a clause that allows me to "demand"
cancellation of a ticket but have to use this ability carefully. We
do, though, maintain funds which can be used to reimburse someone the
cost of what is a "legal" ticket in "unfortunate circumstances" such
as the B&Q one quoted.

Interesting insight. Thanks