The figures are all from Artizan Designs' Second Afghan War range. The Sikhs are from packs NWF 0105 - Sikh Infantry Advancing Afghan War and NWF0106 - Sikh Infantry Advancing II. Each blister pack comes with 4 random variants. The British Officer is from pack NWF0010 - British Officers Afghan War which also includes 4 figures.
Regular infantry for The Men Who Would be Kings are 12 figures strong and as you can see are based individually which allows easy casualty removal. In addition they be used for skirmish style games like In Her Majesty's Name.
Above is a size comparison of showing the Indian Army HMG from Copplestone Castings Back of Beyond range with Artizan Designs. They match perfectly for compatibility.