If the window operates in one direction I would suspect the switch is bad. I have had this happen to non Rover power windows before. Replaced switch, problem was solved.
When troubleshooting I always start with the easiest/cheapest and work my way to hardest/most expensive fixes.

 

Seems to ALWAYS be the SWITCH, and NOT the regulator and/or motor. Just go with that!

 

Thanks Yikes i am going to order a switch. The dealer told me it was the regulator. Huh

 

Canlandy--- If you tried the regulator on the passenger side using the passenger switch and the regulator operated up and down, it is certainly your driver's side switch... not the regulator. Ironically, I was incorrectly told the same thing by the LandRover dealer in Birmingham Michigan after their physical inspection when it was in their possession for another matter (a matter that they also incorrectly diagnosed, but that's another story.) In any case, since I'd previously tested the regulator on the passenger side as you did I knew they were wrong, and so installed the switch myself and all is still fine now 4 years later.