Here is some useful information taken from the above mentioned book by Carter.
It may be of benefit to some.
"1894. Wolverhampton abandoned the 1880 livery and fell into line with that used at Swindon. The old livery could however still be seen as late as 1900.
1894. For some time after this there were two locomotive greens in use, one described in sources as “Deep Holly” used at Wolverhampton and very similar to the previous Swindon green and the other described as “Middle Chrome green” used at Swindon. This latter shade was introduced on the 7’ 8” 4-4-2 engine No 3031 “Achilles” and was eventually adopted as standard up to 1951."
Tony.