Hussars is a good possibility, although I cant link the Pagri flash, which doesn't mean much
I still find that four pocket tunic unusual. Note the seated man appears to have the standard 1902 KD tunic with pointed pocket flaps, which would only have the two upper pockets.
Those Bombay Bowlers they have were more commonly seen after ww1, but I believe some were worn during the war as well.
CB