Hmmm, crimean highlanders, yes why not!
I even thought to use guards command to make my 1 unit of wessex guards of 15 figures into 2 units of 10 figures each.
But if you want to increase the range of colours into your armies, see the uniforms of Italian armies (War of Independence/Risorgimento/Garibaldi and Co).
There you will see, apart the blues, lots of greens, pink, red, purple and so on.
Or imperial french armies with blue and red but also white, sky blue and so on!
Another inspiration is to see what colours the ceremonial uniforms of even today have: yellow jacket with sky blue pants, or golden yellow uniforms, or even white uniform with red epaulletes and piping. Lots of choices around the world!