Already had a look on there, and done a google, from what I can find the landrover site gives exterior dimensions. If you download a brochure it also gives the maximum length of loadbay and height and even the biggest box you can get in it. But it doesn't give the size of the well between the rear arches or the height of those arches. Which is the measurement I needed.
Unless I've missed something, which is possible I guess!!