Prior to Federation on 1 January 1901, the official flag of the Australian Colonies was the flag of Great Britain, the 'Union Jack'. However, the British colonial Naval Defence Act 1865 authorised the establishment of naval defence forces by the colonies and specified that such naval vessels should fly a Blue ensign with 'the seal or badge of the colony in the fly thereof'. Such flags were designed and adopted by the colonies. The flags of the Australian colonies date from 1876 (New South Wales and Queensland), 1877 (Victoria) and 1895 (Tasmania and Western Australia). South Australia did not adopt a flag until 1904. Over time, use of these flags was extended beyond mere display on naval vessels.[3]

The concept of a distinct national flag predated Federation. For the last two decades of the nineteenth century, the Australian Natives Association and the Australian Federation League displayed and popularised a design encompassing a Union Jack and the Southern Cross. One of the earliest documented official requests for designs for a national flag came in a dispatch dated 29 November 1900 from the Secretary of State for the Colonies in Britain.

Competitions seeking designs for a national flag run by the Melbourne Herald and the Review of Reviews in 1900 were well supported. On 29 April 1901 a notice was placed in the Commonwealth of Australia Gazette inviting entries in an official competition, offering a prize of £75 to the winning entry.

From the 32,823 entries received in the 1901 competition, five substantially similar designs were selected as joint winners.[4] A photograph of the winning design, a composite 'embodying the general ideas of the five successful competitors, but different in detail',[5] was published in the Review of Reviews on 20 September 1901.

The winning design was approved by King Edward VII in 1902. Federal Parliament passed a resolution on the 2 June 1904 to fly this flag 'upon all forts, vessels, saluting places and public buildings of the Commonwealth upon all occasions when flags are used'. While the design and uses of the flag were proclaimed in the Commonwealth of Australia Gazette, it was not until the Flags Act 1953 that legislation was passed prescribing the form and use of the flag. Section 3 of the Act states that the flag (illustrated in the First Schedule to the Act) is 'declared to be the Australian National Flag'.

The Australian Flag consists of three parts set on a blue field. The first part is the Union Jack, illustrating the link with Britain. The second aspect is the Southern Cross, representing Australia. Finally, the Commonwealth Star represents Australia's federal system. Originally, the Commonwealth Star had six points (for the six states), but, in 1908 a seventh point was added to represent the territories of the Commonwealth.

The Archives office in Canberra holds a range of records relating to the Australian flag. These include records on the 1901 flag design competition, information about the design and use of flags, the drafting, enactment and administration of flags legislation, and artistic copyright applications for flag designs. The table below lists some of the major record series containing information relating to the Australian flag.