An interesting photo. The group seems made up of a mixture of ranks and regiments and is very relaxed. I can't see any medal ribbons so pre-WWI, but I'd have expected the senior NCOs, at least, to have Boer War or India service ribbons. I wonder whether these are not Regulars, perhaps instead this is a group of Territorial soldiers at camp shortly before the War ?.
I don't have the expertise to interpret all the detail but suggest this enquiry should be moved to the Armed Forces board for the experts there to view.
Maec