I mixed exact amounts according to the formula and mine are much much darker than your mix.
The Vickers that I owned was a much darker green than that on your first truck . The FGT has a more green colour. Closer to vietnam era jungle green but brighter.
http://www.awm.gov.au/collection/P08521.005
My feeling is my green is greener and my light stone is paler, greyer and lighter than the formulas produce. The Humbrol Pale Stone 121 is very close to the pale colour on the Stuart and the green start colour 159 is closer to the green than the mixed colour.
The Vickers was painted very much the same as the one at Pucka which I took to be the dark pre 1942 green .
http://en.wikipedia.org/wiki/Light_Tank_Mk_VI