A retired Australian police detective has claimed that
anti-monarchists attempted to assassinate the Queen in 1970, by derailing her train in a cutting near Orange, New South Wales with a log.
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.
Det. Supt. Cliff McHardy (retired) was involved in the investigation of the incident, but was hampered by a ruling keeping the incident secret. To this day, it's not clear who was behind the plot; in fact, their description as "anti-monarchists" seems more tautological than anything else. (It could have been anyone. One of various flavours of Communists, perhaps, or some fifth-generation Irish-Australian still angry about the potato famine, or some troubled individual just wanting to make the mind control rays stop, or perhaps none of the above.)