The British and US systems of government have had substantial influence on the Australian system of government. In fact the Australian federal Parliament has been referred to as a "Wash-minster" model – a combination of the US "Washington" model and the British "Westminster" model.
Before 1901 the Australian continent had six partly self-governing colonies which were modelled on the British Parliamentary system. When developing the Australian federation model in the 1890s, the British Parliamentary model was very influential. This influence can be seen in many aspects of the appearance and function of the two chambers of the Australian Parliament. The idea of responsible government – a government elected by the people and accountable to the Parliament – is a significant British contribution to our system. Also, Australia's version of the separation of powers – the division of power between the Parliament, the executive and the judiciary - owes much to the British model.
The major influence of the US system can be seen in the overall model of Australian federation – particularly independently governed states working together under a central federal government structure. Also, the representative structure of the Australian Senate draws heavily on the US model of the Senate.
Need more information? Check out this Closer Look paper comparing the Australian Parliament and the US Congress.