This will do totally out me, so name change coming up soon.
SIL parked on a patch of grass over the road from my parents earlier to collect her DC who my mum was watching for her. I was there with my DC. When she went back to the car this note had been left for her.
My dad is fuming, if they wake up with a horses head next to them in bed a la the godfather they'll have got off lightly.
a) the grass belongs to the council
b) it's a rented property and the owners are friends with my parents and they know it belongs to the council (there used to be good natured joshing about getting the prime spot on the grass when all us kids lived at home so there were 5 extra cars to park, plus partners 
)
c) my dad is friends with the chap that built the house in the first place and it definitely belongs to the council
d) the council maintain/mow it
I predict every visitor to my parents will now park there, my dad was moving talking about moving his car there as I left.
Would we BU to point out it doesn't belong to them so anyone can park there as and when they fancy? It doesn't cause any obstruction to anyone's drive/right of way.