I've also received so-called 'ghost tickets': PCNs issued but not placed on the vehicle. The parking attendant (PA) spots you, say, dropping someone off on a single yellow (allowed, for up to 20 mins depending on the borough) then issues a ticket to your car, without placing it on the vehicle. PA then downloads their handheld machine's data back at base and the PCN enters the system, with a ?100 final demand arriving on your doormat a month later. Got off because I challenged it under the 'Offence didn't take place' rule and demanded photographic evidence. Let off because of a 'technicality' without apology. many friends have suffered this and just paid up in fear of not getting a successful appeal.