Anti-monarchists attempted to assassinate the Queen by derailing her train as she toured Australia almost 40 years ago, it was claimed today.
A retired senior detective has broken his silence to reveal the alleged plot to kill the Queen and the Duke of Edinburgh and to bemoan the fact that the culprits were never caught.
"It was one of the big regrets of my police service," the former officer told the Australian Lithgow Mercury paper.
Retired detective superintendent Cliff McHardy, 81, said the conspirators put a log in the path of the train as it travelled through a winding cutting towards the town of Orange, near Sidney, in April 1970.
They had been aware of the service's schedule and had managed to avoid a "sweeper" locomotive that passed through the area a short time before.
But the log failed to derail the train carrying the royal party and became stuck under its front wheels, bringing the train to a stop at a level crossing.
Mr McHardy told the Daily Telegraph that vandals were not behind the incident.
He said: "The log had been moved on to the line in darkness, by one or two people who had prior knowledge of the area."
He added: "Had it been going at the speed it was allowed to go, it would have derailed, the railway people told us."
When the former senior officer began working with colleagues to track down those responsible, he found his job hampered by a ruling from Government officials not to publicise the attempted derailment.
Questioning the public proved difficult as they could not reveal the nature of their inquiry.
The remaining time of the five-week tour passed without any problems and saw thousands turn out to see the Queen.
Buckingham Palace made no comment about the alleged incident.