In 1995, Elliott joined the Australian Army and commenced his officer training at Royal Military College, Duntroon, attaining the rank of Captain in April 1997. Taking 18 months' leave, he worked as Press Secretary for the Hon. Peter Collins, QC MP who was elected NSW Leader of the Opposition following the 1995 state election. During 1999, Elliott was Director for the Australians for Constitutional Monarchy campaign against the referendum for Australia to become a republic; for which he was awarded the Centenary Medal on 1 January 2001 for service to the constitutional reform debate.