Thanks Wojtek and Terry.
I have been trying to decide on Sutton Harness colour. The information ranges from "Buff" to Khaki, to RAF Blue. Add to that the different apparent tones in B&W photographs and it is a bit of a minefield. (Even discounting orthochromatic film!!). In addition "Buff" in British parlance runs the range from almost white/light brown to quite yellow.
I've decided against my prefered RAF Blue as whilst I HAVE seen postwar belts of that colour, I haven't seen any definitive evidence of wartime Suttons as blue. This leads me to believe that the alleged blue of the IWM Spitfire (as per the Patrick Stephens, 1970's Airfix book) may be a postwar harness. So the various dark belts in photos could be any or all of:
a) dirty,
b) orthochromatic film and yellow,
c) khaki but more "English Uniform"
Now the problem is illustrated particularly by the first picture below where the uniform could be described (although, of course, not "officially" described) as being Khaki Uniform with Khaki webbing, Khaki puttees and Kharki helmet. The pictures following give the idea....
But putting all of that aside, I didn't like the pristine and very yellow colour of my original Sutton Harness. As it is NOT dated, I have no way of knowing it's date of manufacture, although I have seen a 1938 dated example of the same colour.
However, after two years of use, half of that wartime, I figure a liberal amount of oil and grunge will have attached themselves. So the final three photos are what the coffee dyeing has produced and I am relatively confident that it is a plausible colour. note even those three photos under slightly different lighting, give quite different impressions.