Yeah, thanks for the heads-up gemsdad, Gazbo is right. On 300 Tdi Disco the windscreen is a bonded fitting, the rubbers are pushed/glued/whatever on afterwards .. if the windscreen's leaking it's nothing to do with the external rubbers!
Having said that ... there is a chance that water gets in between the rubbers and screen, and gets into the vehicle via a convenient hole, bad grommet, rusty bit (would you believe?) etc.
A sealant and gun would be best, but don't try to remove the external rubbers before you get new ones, they don't come off easily. Better, as a 'fix' rather than a full-on repair to just lift the edges and squeeze the sealant in. Mine went on the top edge, water making it's way all over, but sealer worked fine forever after ..
PS, if you wanna do a full repair, this might help ..
https://www.landyzone.co.uk/land-rover/disco-1-300tdi-windscreen.286577/