Seat Belts and the Law

I've searched LZ but to no avail: please can anyone clarify the current seat belt legislation? My SWB Series III is now a truck cab, which is great but, of course, I've lost my seat belt mounts.

Is it lawful to fit and use only lap belts? And if so, do they have to be inertia reel jobbies or are statics ok? Alternatively, what is the best (ie MOTable) way of securing 3-point belts is a truck cab or altogether topless????

Sorry to sound like a newbie but this is unchartered territory for me and it's important enough to get right. Besides, there must be loads of relevant experience on here.......

have a look at the "Seat Belt Guide" on this
Exmoor Trim & Trakkers

Turn the belt mounting on the bulkhead behind the seat so that it is now inside the cab.Floor attachment remains in same place.Some people have even fitted inertia reel belts ,but using a spreader plate lower down on the bulhead .This has been covered some time ago in full picture detail in one of the Landrover magazines.

No lap straps are not legal.