Their rejection is obviously wrong re the location, but is only a reply to an informal challenge.If you want to take the matter further, you will have to wait for the Notice to Owner, and submit representations against that. Looking at GSV, it is clear that parking has been taking place here for many years so why have PCNs now started to be served ? Three possibilities, (1) a new CEO not knowing locally tolerated parking where a sign is present and overzealous enforcement is clearly unfair, as here, (2) "order from Headquarters" to go out and serve as many PCNs as possible to get the money in, and (3) somebody local has complained.
Did all the parked cars get PCNs ?
The law is that the yellow line covers the whole road, and that includes footways and verges to which the public have unrestricted access. So the PCN is correctly served.
Apart from persuing this through the process, I suggest your friend gets hold of the local councillors to get pressure placed on the parking department concerning this overzealous enforcement that is clearly nonsensical in the circumstances, and that parking has taken place here over many years, GSV views showing cars parked outside the houses go back to 2011, 15 years ago, and all show parked cars.
https://maps.app.goo.gl/RBbJuARxf6fhe8wK9If she is prepared to stand her ground and take them to the Traffic Penalty Tribunal on the appeal basis of "legitimate expectation" (of no enforcement due to the site circumstances), then she must now wait for the Notice to Owner, sent to the name and address on the V5C Registration Certificate for the car.
