Sir Doris is correct
You cannot legally drive a motorised vehicle along a Restricted Byway
The only unsurfaced rights of way you may drive a motorised vehicle are BOATS (Byways Open to All Traffic) and ORPA's (Other Routes with Public Access). Even so, BOAT's and ORPA's may be subject to a TRO (Traffic Regulation Order) either seasonal, temporary or permanent, and as such become illegal to drive a motorised vehicle along them.
Note the term "illegal" - if caught, you can be prosecuted.
Lawrence
Green Lane Association Member
http://www.glass-uk.org/