The Queensland Steam Shipping Co. had been formed in 1887 by British India Steam Navigation with its flag being red with a white saltire which was the BI colours and basic design in reverse. In 1887 it was amalgamated with the Australasian Steam Navigation Co. to form the Australasian United Steam Navigation Co. Ltd..
This British India Steam Navigation Co. page shows a red swallowtail, white saltire, rather than a rectangular version. The BIShip page is the only source showing the swallowtail I am aware of (it may well be erroneous).
Queensland Steam Shipping Co. The image as shown by Jonathan is based on my information which in turn originated from that shown in The Log 8/1986 in an article by Bob Tompkins. With Bob having been an expert on this subject, especially on his own Australian scene, as this is what he showed I would expect it to be correct. Having said that, it does illustrate the problems with written descriptions which in most cases will result in different interpretations by different people. With Bob himself now deceased I cannot check out his sources or what he meant as he was also writing of the connection with the company and BISN, but on re-reading his comments in The Log he does state that "the flag is a reversal of the BI flag" even though he may have only meant that the colours were reversed. So whilst correct as far as the colours was concerned this was obviously incorrect for the flag design as the BI flag was a swallowtail and the saltire did not extend to the fly. Therefore, in my wisdom I "clarified" things in my comments by stating that it was the "basic design" only meaning that it was as a plain flag bearing a saltire and if Bob's image is right then I feel that this was a better way of describing things.
The version found by Jan on the biship site now has me wondering as at least one of the sources given is familiar. I have sent a message through to the site in the hope that it is still active and with luck we will get to the bottom of things, but for now I am not sure which was the correct version.
Further to my comments above, regarding the link supplied by Jan to the biship site and their showing of an exact reversal of the BI flag, it has now been ascertained from the proofs of the Bob Tomkins article that he did show it as a red rectangle with white saltire and referred to as being the "virtual reversal" of the BI flag. The dropping of the word "virtual" in the final printing results in an incorrect interpretation able to be made and this seems to have occurred with the World Ships Society records describing it a reversed BISN flag sourced from Bob Tompkins. It is my conjecture that the persons assembling the information for the BI site would most likely be UK based and involved with WWS and would therefore go to that source's liveries records. Lacking a definite source to the contrary I feel this is a reasonable conclusion. For interest, two sites show the rectangular flag but as their sources are not known this does not prove anything