Not true, Eddie, or all the drive offs would get away with it.
"The traffic warden can:
fix the ticket to your windscreen
hand a ticket to whoever seems to be in charge of the car
send it by post under certain circumstances.
By law the PCN must be issued within 28 days of when the traffic warden saw the parking rule was broken or it was caught on camera. The guidance local authorities use says they should issue the PCN within 14 days, but they do not have to follow that guidance"
http://www.adviceguide.org.uk/wales/consumer_w/consumer_cars_and_other_vehicles_e/consumer_driving_and_parking_e/consumer_parking_tickets_e/parking_tickets_on_public_land_where_the_council_is_responsible.htm
When can the PCN be sent by post?
The PCN can be sent by post if:
it was being issued as the vehicle was driven away, or
the driver or passengers were abusive, or
evidence of the parking rule being broken was caught on camera.