If my memory srves me, the 'Tommies' were a good sized herd kept in a triangular-shaped paddock somewhere (near the Giraffe) in the centre of the Park. But the paddock seems not to exist anymore.
I had thought they were in the region of cheetah rock to what is now the entrance to the asia drive through area. Somewhere in the middle of the park seems to be as close as we can both recall, but it is a large zoo!
I think they moved a bit! I have a feeling they were once in a paddock near where the wild horses are now. I also think they were in the paddock where the scimitar horned oryx are at a later stage.