Tis nice, ain't it. It's an 1870s/early 1880s India thing, mixing the khaki top with the blue trolleys. You would see some British regiments dress like that in the 2nd Afghan War. I've not seen a British khaki tunic with coloured cuff facings personally (and bear in mind it's for a fictional campaign), but in the Indian Army of that time you see it, so it ain't without precedent.