British infantry in loose trousers without puttees do appear quite frequently on period photographs and drawings of the second Anglo-Afghan war, so they'd be a nice addition to the range.
And since I've already hijacked my own thread, may I suggest mounted Senegalese for the MOD range ? They add a nice bit of variety to the cavalry, which were mostly
Chasseurs d'Afrique and Algerian spahis during the pre-1914 campaigns.
These came in two flavours : the regular Senegalese spahis with their distinctive red uniform...


... and what appears to have been ad hoc detachements of
tirailleurs who effectively became mounted infantry :

Let's not forget Moroccan cavalry for the other side : there was an awful lot of it at Sidi Bou Othman ;