On a single track residential road the car in front of me indicated and pulled over towards the centre of the road in an effort to park in an authorised parking bay on the opposite side of the road.
As there was enough space to pass safely on the inside of this car I preceeded to do so WITHOUT mounting the curb. At the point of almost passing this car the other road user turned their steering wheel hard to the right and continued to reverse into the parking space on the opposite side of the road so that they would be facing oncoming traffic. This action caused their front nearside headlamp area to scrap against my rear door and bumper area causing paint damage only. This incident occurred during the day.
I did exactly the same thing as you a year or so ago....and unfortunately it was deemed as being my fault as I should have waited for the other driver to complete their parking!!!!!
I did argue that I thought that he had finished parking, and after about a year (yes a year) it was decided to go 50/50.
Insurance law states that the onus is on the driver making the manoeuvre to check its safe to do so. As he has hit you he obviously did not check his mirrors.
I don't know about the law, but when I was learning to drive we were always taught that when doing a manoeuvre (eg parking as he was) you should always wait until the road is clear of other traffic, I think he should have made sure you were out of the way before beginning his manoeuvre
As a ADI I can say that the person doing the reversing should wait until the road is clear. In the circumstances you quote the reversing car has turned into your vehicle and is clearly reaponsible for the accident. Treacle