Don't know if this will be rea as its an old topic, but I think it needs some clarification.
Its quite simple, if your tow vehicle has a max towing weight of 2000kg, this is what should be the max gross weight of the trailer, regardless of contents; eg.
horse box weight 900kg
Horse 1 500kg
Horse 2 500kg
Total 1900kg
As long as the trailer is plated as less than 2000kg, the Freelander can tow it, but as its more likely to be 2500kg or 2700kg, it can't, even if its empty.
Think of it like tthis;
You get pulled over and VOSA weigh the trailer and you're under the 2000kg, how do they know that you are not going to unload and load up with heavier items/horses . . . ?
Now that VOSA have clamped down on farmers and lorry drivers, and in doing so, these have got all (most) of their vehicles and trailers legal, they are aiming at horseboxes, caravans and normal trailers!