What I'm speaking of is the infamous "One Gun Salute" where Lights woke up all of Sydney in October of 1900. I have often wondered if Miss Sylvia Hawley-Wilson was in Sydney when the gun went off-- and how he 'fessed up about it, if she was!
Here is a newspaper article about it
WHAT HAPPENED AT FORT DENISON
A Strange Story
Who fired the gun?
The police are engaged in investigating a peculiar occurrence which is reported to have taken place at Fort Denison the other morning. The authorities are strangely reticent about the matter, but from what can be gleaned, it would seem that either a big practical joke has been played by someone, or else there are in our midst persons of a very strong pro-Boer temperament. The police are busily engaged in looking for an explanation.
Just as the Post Office clock had struck the hour of 1 a.m., a gun went off at Fort Denison, breaking some of the windows and, the story goes, putting the red light out. How it happened, nobody seems to know. On the tower are several large guns of an obsolete pattern, and it is one of these that is said to have gone off. Moreover, it has been stated that in the morning, a flag with the Boer colours was found flying on the tower. But, whilst this has not been positively denied, an official communicated with last night said he ‘never heard of such a thing.’ At the same time he admitted having received a similar report. A man was dispatched to examine the guns, with the result that he reported that one of them had the appearance of having just been fired. A direct question as to whether it had been fired met with the answer. ‘That remains to be proved.’
Meanwhile the mystery continues and all sorts of stories, possible and impossible, are going about. One is to the effect that a boatman saw a man pull over to Pinchgut; and, making his boat fast, climb up the tower. It was too dark to see what he was doing, and though he watched him for some time, thinking his movements somewhat mysterious; the boatman took no particular notice of the occurrence until he suddenly heard a gun go off. A fuse is supposed to have been employed, and it is also clear that the gunpowder was carried to the fort.
The Daily Telegraph, Sydney Australia, October 11, 1900, p.7
Thanks to Inger Sheil for locating that for me
The best account of the inside story is Lightoller's own, found in Chapters 27 and 28 of
Titanic and Other Ships
Pat W.