So my drawing isn't perfectly to scale, as I forgot to leave room for our garden... But I couldn't be bothered to do it again!
However - I've just gone into my kitchen to prepare dinner and seen a car parked slightly across my driveway, and actually on the grass of my front garden (black car in diagram) I assume they're visiting neighbours, as I can hear a voice I don't recognise in their back garden.
I don't have to go out, but I think it's a bit rude to park on my grass! There is no available street parking here (small cul de sac, already too many cars)
Do I knock? Or leave it as they'll probably go soon?