Having discovered where Bristol Parking Services park, the next issue becomes how.
Diagonally across three of the bays and a "do not park here" bit of the Bristol Parking Services area was some kind of towing van.
The kind of van you use to tow vehicles parked across three bays and a "do not park here" bit of a junction. They are lucky there were no Bristol Parking Services staff around to enforce the regulations.
There was, however, a BPS staff member to enquire about why someone was taking photographs -whoever they were they didn't try the "you can't take photos gambit". They did explain that there was actually a good reason for these vans to be here. And he was probably right: there are so many people parked illegally round the city there was nowhere else for Bristol Parking Services to park their towing van.