There are a million posts on this, so quite common
Rear window clips, feel under the rear window for points under the clips, these need sealing. Around the window trim, breaks in the rubber. Rear light seals, can be renewed from Jezzer, boot rubber trim, breaks in it can leak. Side chrome strips, the clips fixing these are another weakness, as is a vent behind the inner boot lining, covered in paper which obviously isn't good
The boot hinges also are known to leak around the fixing bolts. So, there's a few.
If Rover made submarines
