From the rear there are not many clues to help identify this particular car's age. I can ramble about what is not helpful. The only clue on the body are the later type door mirrors and he badge above the boot lock which appears to be a Rover type used from 1990 onward. However, even that doesn't say much as there are lots of aftermarket badges and mirrors available.
Were I schooled in reading British plates I am sure the one shown on the car could be decoded to reveal the car's age. The original British plates remain with the car through its life and are part of the car's legal record.
EDIT: See the link below which tries to explain the THREE coding sequences found on U.K. plates. If the boot badge is original to the car, the "H" prefix on the plate would confirm this as a 1990-1991 car.
https://www.regtransfers.co.uk/car-registrations-uk
EDIT2: I asked on another message board and my acquaintance Rich from Mini Spares answered about the license plate...
"
HF53KLM is currently on a red Skoda Fabia which was first registered September 2003. Its currently taxed and tested, so what a copy of its plate is doing on a rover mini in the usa is a mystery."
I will post any additional information as I get it.
EDIT3: After a couple of days of discussion on a U.K. message board the only thing I have to report is that most respondents suspect the HF53KLM is an arbitrary copy made by a U.S. owner who wants their car to run British plates. Clearly the car in Basil's picture is not the red Skoda mentioned as currently running those plates in the U.K.