The Army Medical Service was formed in 1873. It was not particularly successful or popular and in 1898 it was reformed again to become the Royal Army Medical Corps.
I wanted to use the Perry Sudan War medics set for both the Sudan War and Indian/NW Frontier service. The uniforms depicted in the following images are fairly accurate for the Sudan.
In India and Afghanistan they may have worn khaki. However I'm assuming at the time of the Second Afghan War they were probably still wearing Home Service uniforms with the addition of the ubiquitous Foreign Service helmet.
Thanks to Jeff Lower who helped me with the red trim and arm badges.