In my opinion, you are prohibited from moving the offending vehicle (even a few yards) without a Court Order. To do so could result in yourself being prosecuted because you are Not legally entitled to interfere with the car concerned. Read the following Official Police Link and note the last part of the first paragraph which reads .... "Those who have lawful authority and in fact a duty to remove vehicles from roads or other land include the police, local authorities, traffic wardens, parking attendants and civil enforcement officers".
https://www.askthe.police.uk/Content/Q441.htm
It might be worth further contact with the Police and also an approach to your local Authority, along with an e/mail or telephone call to your local Councillor.
Hans.