Quoting: kochanie
My friends have recently bought a house in what they thought was a nice street with what they thought were nice neighbours
Living in a "Nice street" means that people respect each others' parking areas, an important issue.
Quoting: kochanie
because both their cars have been parked in front of his house
I would also complain about this.
Quoting: kochanie
it is a civil liberty to park in your own street
No, you are wrong. This is a complicated issue, but you are basically wrong.
Quoting: kochanie
'DO NOT PARK HERE' in Polish
Maybe he thought they couldn't speak English?
Quoting: kochanie
'Oh, so you can speak English then'
I rest my case.
Quoting: kochanie
she's not a bad person
I'm sure she's not, but English house and parking law, written and unwritten are to be observed.
I see this being normal English behaviour towards inconsiderate parking, anyway where is the "Constant bad-mouthing" ? this is one example of bad manners by both parties.