Dales right I think, check where DVLA stand on 'private' and then get your proof of fact your car is now on private land, if indeed it is. I had a bad experience quite a few years back, had a Mini had bought and planned to restore out front of house and wasn't taxed (naughty me so fair cop guv!) Never drove it or anything but in a close so thought doing no harm. Anyway, this was in days before SORN and they sent me a bill for not just when I had owned the car ( a few months) but for all the years it wasn't taxed as off road with previous owner. Bill was about £1500 so forced me to scrap the c