If you have just escaped from the car park at Waitrose, Richmond without paying, you can thank me. The clock at the entry and exit machines was around 30 minutes out. Waitrose say it was only 10 minutes out. My case, Your Honour, is that I entered at around 11.40 am whereas the time printed on the ticket was 11.10 am. When I inserted the ticket in the pay machine at 2.11 pm as a test, it asked for a penalty payment of £25 because, according to its clock, I was over the three hour stay limit.
Waitrose accepted that there was a problem and put an engineer on the job. When I pressed my complaint on behalf of customers who might be misled into paying more than they should, they put the barrier up at the exit point and posted a staff member at the pay point with a view (hopefully) to warning customers not to pay.
It's wise not to rely on your watch to log the correct time when you leave your car but to check what the ticket would have you believe is the correct time or you could be caught out. For anyone who, whenever and wherever, is caught out in this sort of situation, you will find the wording for a court claim in Breaking Law.
Oh and Waitrose let me out without paying anything. It must be my smiley face.