It looks like the 1908 pattern web equipment he's wearing (the ammo pouches). That was worn up until WW2. The rifle he's carrying also was used anywhere in that time period pre WW1 to after WW 2. The khaki tropical uniform could be for a member of the Indian Police Service. If you have a name, you could try the British Library India Office Records branch to see if they have any records. Here's a link to the ones they have for the Indian Police Service-
http://www.bl.uk/reshelp/findhelpregion/asia/india/indiaoffi...