However, it was not until 2009, almost 40 years later, that Detective Superintendent Cliff McHardy decided to tell the local newspaper, the Lithgow Mercury that he believed someone had tried to derail the train and kill the duo.
"My investigations showed that the log was deliberately placed on the tracks," he told the publication, adding the train line had been checked an hour before the pair's arrival and nothing was there.
This made him very suspicious.
The late Mr McHardy went on to say that if the train had of been travelling any faster it would have been a "catastrophe."
He further claimed that police investigating the incident were told not to say anything and to keep quiet in order to keep Australia's reputation in tact.
"They said keep it out of the press because the Queen is still out here and if it had broken the next morning there would have been all sorts of trouble and we can do without that in a small country town."
It is understood that at the time, the NSW Police were looking into the matter, however Buckingham Palce denied any knowledge of it.