Curious provenance? Perhaps, to say the least!
Post a pic of your truck. I see you're in the U.K. Perhaps you have a prototype truck for a particular (non-UK) market, but most likely it's just a winch or an unusual fitment item. Any defender with catalogue bits added by the factory got a LRSV plaque/sticker regardless of whether it was a dual battery or a telescopic boom transmitter.
They were making NAS trucks during that time, so who knows! How many owners has the truck had? Where? Is it unusual in any way? i.e. V8 or integrated roll cage? Large boom or cherry picker? Anything that would be non-mass market specific items for a uk home market truck.