If it is declared off the road and not in use, but it is still parked "on any" piece of the public highway then it's a £60 automatic fine.......and you'll find that you can never trust your neighbors.
I had a car parked up a little side street for a couple of months, totally off the beaten track and away from traffic wardens. 4 days after the tax ran out a ticket appeared on the windscreen. Now if a neighbor didn't make the call then it was a pretty darned diligent traffic warden?