OmG I answered this and it disappeared before I could post it. Long--short:
@Tony: Yep. but I'm pretty sure that the sculptor, though not the painter, had access to Kiplimg and King. The back is certainly from the Buffs as portrayed in pl 7 of that work, but the painter got the color(s) wrong.
@Paul. Good question. Regulations in 1743 updated the pole weapon of a company officer from the half pike to the spontoon. see pl. 7 fig. 19 in Barthorp's British Infantry Uniforms. and discussion, p.36. This figure, though, is almost certainly taken from a well nigh unimpeachable source, The Thin Red Line by the Fosten bros. You will find the illustration in the middle of Pl. I, complete with fusil.
I agree with Einion that this a splendidly posed and sculpted piece, and the problems with the painting can be readily corrected.
Hope this helps.