Like Snazy I have been caught on that one but after the 4.00pm deadline, because the queue in the PO took a lot longer than expected. And you can't deny it when you see the photo of yourself driving your car, number plate visible and all.
Please watch out if you stop outside because there is a loading bay as well as a short-stay parking area in off-peak times, and apparently the cameras can get you if you are not actually loading.
Better to park in Ravensbourne Road around the corner where you can hide from the camera!