The notebook actually contains handwritten copies of eleven articles published in the Argus (Melbourne) newspaper from 28 February to 16 November 1918 about two murders it called the “Mount Howitt Tragedy”. I subsequently found another five Argus articles about it published in March 1918.
The sixteen articles report the discovery and the subsequent police investigations of the murders in 1918 of James Barclay, the manager of Wonnangatta Station in the East Gippsland highlands of Victoria, and his cook, John Balmford. Now known as the Wonnangatta mystery, it has never been solved. For more details an easy place to start is this Wikipedia page, which has references to many of the books written about it over the years.
When I first saw the catalogue entry in 2005, I misread it as meaning that Upfield had actually written the article, but that seemed most unlikely as he was in England with the Australian Imperial Force for the First World War at that time.
It also occurred to me that he may have found and kept the article with a view to using it as the basis for a story or a novel.
The answer is in a letter of 29 June 1934 to Charles Lemon in which Upfield wrote:
For a Sydney publisher who is bringing out a library of sixpenny booklets on the style of the American Blue Book, I have written one on Snowy Rowles and a corker on what was known as the Mount Howitt tragedy which was never cleared up back in 1918.The booklet on Snowy Rowles is clearly The Murchison Murders by Arthur Upfield (Sydney: Midget Masterpieces Publishing, 1934), so the Sydney publisher would have been Bernard Cronin who died in 1968. His archives are in the National Library of Australia but do not include the manuscript.
In the The History of Wannangatta Station, Wallace Mortimer says one possible motive for Barlay’s murder came from a novelist “who had obviously done little or no research into the matter” (Richmond, Vic.: Spectrum Publications, 1980, 121). Mortimer, who was born in 1927, told me late in 2010 that the novelist was definitely not Arthur Upfield but a journalist.
A book called Who Killed Jim Barclay? by Wallace Mortimer was published in 2009 (Milawa, Vic: Wallace Mortimer). In it he claims to reveal “the killers, plural”. He may have solved the Wonnangatta mystery, but the whereabouts of Upfield’s manuscript, if it still exists, remains an unsolved mystery.