If the car park you left your car in belonged to the flats you visited, (not made clear in your post), then I'm surprised your friend didn't offer you a permit to display.
Nobody seems to have queried why you parked where you did when you knew it was private land.
My nephew owns a flat in a block near Horley station including a parking space in the car park which is jointly owned by the flat owners. It is a regular occurrence that when his wife returns from the...