John Harrop came across the picture and poem below in ‘Animal Stories’ by Rudyard Kipling, published in 1932. The illustration is by Stuart Tresillian and appears to show a 2nd Goorkha Rifleman (with dicing on his Kilmarnock hat) looking anxiously at the elephant gun team lumbering up behind him.
This extract about the elephants of the gun-teams is one of several verses giving a voice to animals in military service, and is complemented by a Kipling short story ‘Her Majesty’s Servants’ in which the author, whose tent has been blown down, takes shelter under a gun and hears the animals talking in this way. The rest of the poem and more information about it and the story are on the Kipling Society website.
Another illustration of the elephant guns from the same book: