A stocky and humorous man, Souter wrote short stories, verse, light articles and plays, with a capable and ready pen.

He did a fair amount of painting in watercolor, but his reputation rests on his black-and-white work, which, considering the mass of it, was very even in quality.

Some of Souter's cat studies appear in the children's nonsense rhyme book he wrote, entitled Bush Babs: with pictures (1933).

He was the author of the book and libretto (Alfred Hill wrote the music) for the 1917 comic opera The Rajah of Shivapore, and also designed the costumes.

Souter died suddenly at his home in Bondi, New South Wales on 22 September 1935, and was survived by two sons and three daughters.