It does seem a grey area. We have a similar thing down our road and from talking to neighbours, it seems the chunks of land were allocated to the homeowners by the council so that they didn't have to maintain the lanes anymore. Our lane used to be totally accessible when we first moved in but now some chunks are overgrown with brambles, parts have been flytipped on and one person has erected a big gate to stop anyone coming down.

Having been burgled via this back lane I'm sort of torn as to what sort of state we keep the lane in (eg. since it's been a messy state, there's been no break ins down our side of the road) but it's proven to be a contentious issue - disputes about which tree is on which plot of land, whose responsibility it is to maintain the area, who has the right to block access to people's garages etc.

Will watch this thread with interest...