Mycenius, thanks... Should you also be so kind to mention the paints you are using would be great. I am not aiming for 100% accuracy by the way... I am just looking for a khaki that looks good but also isn't too far off the mark. I hope I haven't given a false impression of what I am trying to achieve.
Unfortunately Rem I can't answer that as the figs I have were an 'opportunity buy' off a chap in the U.S. - I have a second unpainted unit of another 20-figs so have the challenge at some stage of replicating the colour myself and trying to provide a compatible outcome so I can mix the 40-figs together to produce 2 units cotnaining some of each...
For example, I have no idea if the following tone is accurate, but I would like to achieve something like that:
Well I think vLV is looking pretty smashing above and not too far off the right colour. WW1 Officers (most notably in the Colonies) still often had their own tailored uniforms anyway (at least early war) so can have some variance too - but I personally think if you can emulate Frank's colours you've got a pretty good final result there - and the colours did lighten with age (fading, etc) so can be lighter - I have some Schutztruppe in Sudwesters who are probably a bit too light - they err towards a yellowy off-white rather than Khaki (which I'm not sure is very historical)...
Anyway here's some rough photos to illustrate the type of colour I was thinking of - NOTE: I don't think this is necessarily an ideally accurate colour - it's probably too 'light brown' but should give you an idea of the direct to err in - I have taken these shots with the camera hand-held and using a flash (with diffuser) so the colour may not exactly reflect what it really is (especially if your monitor and graphics card are not calibrated to the same colour standard, etc, etc). But hopefully they will illustrate the point about not being scared to err towards a light/faded brown look - I think most people have a bit too much yellow in their Khaki (which should really only be appropriate for the odd British Khaki worn in the 1880's in the Sudan, etc)...
Needless to say your chaps should end up looking many times better than these regardless of what colour 'Khaki' you end up with.
FWIW I think I have to figure out if I can ink or wash (and/or Dry Brush) these chaps of mine a bit to get more detail out and such (before contemplating doing anything with the unpainted 20) - or whether the combination of the Brigade Games figures low detail relief (something peculiar to these particular Brigade figs IME) and the existing paint job mean I'm better to just sell them on EBay and buy some Copplestones to mix with the other Brigade chaps and do all 40-figs from scratch...