I have recently received a ticket from OPC. I was parked at what I thought was Watford station carpark and bought a ticket from their pay and display machine. Turns out I was in an area patrolled by OPC for a block of flats. There was no notice where the OPC area started and the NPC area for the station ended. All the OPC signs were well inside the private area, well beyond where I parked, very high up and with small print. I have appealed, sent in photos showing lack of signage and they replied that they will go ahead to enforce the fine. Has anyone else had problems with this particular area. The advice posted looks really helpful so thanks to everyone who has posted so far. Reej