The British Parliament is traditionally referred to as the "Mother of Parliaments", as it has been the model for other parliamentary systems. In the United Kingdom, Parliament consists of the House of Commons, the House of Lords, and the Monarch, although the role of the Queen as part of the Parliament is generally omitted by non-legal commentators. The House of Lords is unique among those Parliaments that have adopted the Westminster system, in that it combines judicial and legislative functions. However, separation of its judicial functions into a separate body has been planned ever since the original Judicature Act 1873, and in the long run is probably inevitable. (See Parliament of the United Kingdom.)
In a similar fashion, the Australian Parliament consists of the House of Representatives, the Senate and the Governor-General as (nominally) the Monarch's representative (though in practice the Governor-General acts independently of the Monarch), although the Australian Senate is modelled after the United States Senate, not the House of Lords. Unlike the House of Lords and the Canadian Senate, the Australian Senate is elected and has much more power than its British or Canadian counterparts. In the Australian constitutional crisis of 1975, the Australian Senate was able to force the then Prime Minister of Australia, Gough Whitlam, to leave office by refusing to pass the budget. (See Parliament of Australia.)
Closer in that regard to the British model is the Parliament of Canada, which consists of the House of Commons, the Senate and the Queen, represented by the Governor-General. The Canadian Senate, like the House of Lords, is an appointed, not elected, body. But the Canadian Senate contains only the equivalent of Life Peers, lacking any members who hold their seat by inheritance or through a religious office such as bishop. (See Parliament of Canada.)
The New Zealand Parliament consists of a 120-member unicameral House of Representatives from which an executive cabinet of about 20 ministers is appointed. There is no written Constitution. Queen Elizabeth II is Queen of New Zealand and is represented as head of state by a Governor General. (See Politics of New Zealand and New Zealand.)
Parliaments originated as meetings hosted by the sovereign of the leading nobles and commoners of the kingdom; this explains the Queen's role as part of the British, Australian, Canadian and New Zealand institutions.