Queensland State Archives posted a photo:
On 29 November 1917, Prime Minister Billy Hughes made a speech at Warwick railway station during his campaign for the plebiscite on conscription. During the speech an egg was thrown at Hughes. He ordered a local police officer Sergeant Kenny to arrest the suspect, but Kenny refused. The “egg throwing incident” led to the formation of the Commonwealth Police, now the Australian Federal Police.
Queensland State Archives, Digital Image ID 2801