As for the trousers being a lighter shade, I would not be too worried by that. This is a problem that I experienced during my own time of wearing No2 Dress (OR's version of this uniform) because before the barrack dress trousers were introduced during daytime in Summer No2 (or SD) shirt sleeve order was worn. This meant removing the tie and jacket and rolling up the shirt sleeves. A belt relevant to the particular duty, usually a white belt for OR's and the Sam Browne for officers was worn. This naturally meant that the trousers faded more than the jacket. For OR's the option (sometimes insisted upon by the RSM) of stores exchange existed but for officers a new uniform would have to be purchased which is why officers sometimes look a bit more scruffy than they ought. This of course was put down to "style"