I originally did this guide back in 2006 and posted it onto the web. The hosting site has cancelled the page and I have lost my text back up so hopefully the new instructions listed below make sense!
The plastic outer surround can leak at the joint between the metal roof and the surround, often the leak can be cured by simply applying silicon sealant all the way round as indicated by the red line.
To investigate further, you need to start dismantling, some fixings are crosshead screws, others are Torx (T20 from memory) begin by folding down the sun visors and remove the screws holding the plastic visor frame to the roof. Remove the centre screw for the sunroof winder (if manual roof)
Prise out the blanking plate below the centre light to reveal a further screw.
Unplug the light connections and remove the visor assembly.
Next you need to remove the grab handles, use a screwdriver to prise open the cover plates
Then unscrew and remove.
Prise up the cover on the coat hooks and unscrew
Next pull the trim around the edge of the head lining to remove and pull on the alarm interior sensor to remove, then disconnect the wiring.
Next pull on the door rubbers to remove - you only need to remove enough of the rubber to access the clips holding the trim panels in place on the B pillars.
Remove trim clips with a screwdriver then pull the trim piece off - there is a securing clip at the top as shown
Pull the headlining down to access the underside of the sunroof - if you are only doing the front roof, you can get away with leaving the headlining hanging down rather than removing completely.
Unscrew the sunroof winder (manual roof shown - electric will be slightly different), the plastic spacer lifts off. Note the rust on mine where water has been leaking in.
Next unscrew the fixings holding the inner sunroof to the outer plastic frame, pull off the rubber drain tubes and lift the inner drain channel away. I cannot remember the exact details of how the glass comes out, IIRC it just lifts out but it will be self explanatory at this stage.
As well as leaking through the winder, my roof was leaking where the drain tubes attach at each side. For some bizarre reason, Land Rover make a metal drain channel then attach plastic boxes to allow the rubber tubes to attach. They are sealed to the metal with mastic and this degrades over time.
You can reseal these with silicon, I used Arldite because one of the plastic drains had snapped where the rubber hose slides over. I made a new plastic drain from those plastic connector screws you use in kitchen unit assembly (B & Q etc should sell). I drilled out the middle of the screw, ground the head down and Arldited it in place.
Now its just a case of re-assembly, fix the inner drain channel back in place, apply silicon to the underside of the plastic outer piece and screw back together. Next re-attach the winder using plenty of silicon as shown in the photo.
Only other point to watch is when re-fitting the trim panels over the B pillars, make sure the cut out locates over the seat belt mounting bolt so that the adjustable height system works.