I wonder if anyone could offer me any guidance as to an available colour matching the green that the BEF used on its heavy artillery (60 pounders) during the Great War? Thanks.
This topic has come up on this forum before several times, if you look back.
The short answer must be "no" as no-one actually knows what the colour was. Indeed it was not a single consistent colour. There was no codification of paint in those days, merely recipes for mixing dry pigments with linseed oil and a drying agent. It was often - rather uselessly - just called "Service Colour". The colours would have varied from batch to batch and place to place because of inconsistent mixing and ingredients. It was mixed only as needed: it didn't come in cans from a store. The drying agent used could also affect the final colour.
It would, however, have been a khaki green and perhaps browner than the WW2 version. We had no access to green pigments during WW1 and our greens were therefore mixed from yellow and blue earth and mineral pigments with white lead. I quite like the Vallejo Model Air Green G3. The newer AK Interactive Real Colour G3 is a very much browner version. Basically, no-one can call you out for using a shade of khaki green: a green with a brown tinge. Without green pigment we could not make strong green greens (having said which, recent research suggests that all Fosters-built tanks were probably finished in the Brunswick green used on Fosters' agricultural equipment using pre-war pigment stock as no colour was specified).
There was an evolution in the colours artillery pieces were painted before and during WW1. Some older pieces were still painted in the 19th century blue-grey "the colour".
There is an article on Landships II by Peter Kempf about this.
There are a fair number of paintings of artillery in action during WW1. Although the forms of the objects are often distorted according to the modernist style there are often clues to the colours of the artillery pieces. Where greens are represented they seem to be mostly some shade of the later BSS colour Brunswick Green.