RECAP for those who don't have time to read the massive long thread. Please correct if I'm wrong:
OP has a drive that fits 2 cars on if you park in a very specific way. The road outside her house has permit only parking between 10-11am and 2-3pm to prevent people parking there all day without a permit. A permit is available to residents at the cost of £40 per year.
OP came home sick from work at 11am to find two unknown cars on her drive. Her neighbour (Nicholarse) told her that one of them belonged to a carer who comes round to see him and his wife and doesn't have a permit and the other belongs to another random neighbour called Caroline (henceforth known as Carolarse) The carer apologised and moved her car immediately. I'm assuming she hadn't realised that OP did not give permission for her to park there but trusted Nicholarse when he said it was fine.
OP blocked in Carolarse with her car and later her DHs car. Carolarse did NOT come to collect her car yesterday.
OP went out to the doctors at 10am expecting the car to be gone when she returned. It was BUT there is now another random car in it's place!