‘The Mystery of the Blue Jar’ was first published in the UK in issue 233 of The Grand Magazine in July 1924 and in the US in Metropolitan Magazine the same year. Reprinted in The Hound of Death and Other Stories (UK, 1933) and The Witness for the Prosecution and Other Stories (US, 1948). Jack Hartington surveyed his topped drive ruefully. Standing by the ball, he looked back to the tee…