Norman,
If the Royal Artillery sets are the ones Lawrence was talking about, there should be no horses. The crews should be wearing pith helmets, with one or two standing officers holding binoculars or a map in one hand and pointing with the other, and the other ranks kneeling on one knee. One crew should be servicing a small field gun, the other a Maxim gun on a gun carriage.
If the Royal Artillery sets are instead wearing their formal dress uniforms, this may be a two box set of a Royal Artillery Gun Team, which should have a larger field gun being towed behind a limber, on which two seated men with their hands on their knees ride, the other three troopers should be riding on three of the 6 horses pulling the limber and gun, and the final figure should be an officer mounted on a 7th horse.
Describe the two extra horses for me, and I will tell you what they are. They could be mounted officers (there was a mounted Royal Artillery Officer wearing a pith helmet, which would be a separate one figure set), or perhaps they are not related to the Royal Artillery set at all.