It may have been PeterJ who did this first. I did the mod on my Roadster -
Angel Eyes from E-Bay - check various sellers for best price. Technically not legal due to no E-mark but will not fail MOT.
http://www.ebay.co.uk/itm/Angel-Eye-Headlights-headlamp-RHD-H4-for-Land-Rover-Defender-90-110-LED-upgrade-/381048823396?fits=Car+Make%3ALand+Rover&hash=item58b8479e64:g:bpcAAOxynLhR-nKJ
