What is the origin of the song "Two Little Boys" sung by Rolf Harris?

From Wikipedia
"The song would appear to have its origins in the fiction of the Victorian children's writer Juliana Horatia Ewing, whose book Jackanapes was a story about the eponymous hero and his friend Tom, who having ridden wooden horses as two little boys end up together on a Napoleonic battlefield. There Jackanapes rides to the rescue of the wounded and dismounted Tom. Jackanapes nobly replies to Tom's entreaties to save himself, "Leave you"? "To save my skin"? "No, Tom, not to save my soul". And unfortunately takes a fatal bullet in the process."

The song was popularized on the vaudeville circuit by Harry Lauder in 1902.

Rolf Harris' rendition was done in 1969.

https://en.wikipedia.org/wiki/Two_Little_Boys