I have received several PMs asking me to post some info about New South Wales marriage laws in the 19th Century or at least post some links to earlier threads on this.
So, January 1788, First Fleet arrived in Sydney, males landed and commenced to erect tents for accommodation. February 1788 the female convicts were landed. February 1788, marriage ceremonies conducted.
1810 General orders issued by NSW governor, including encouraging marriages (I note that this governor, Lachlan Macquarie, was married to his cousin, Elizabeth Campbell).
1823 Charter of Justice - establishing Supreme Courts ie courts with authority to rule on validity of statute laws. - so any English law after 18 July 1823 had NO effect (unless they expressly named the particular colony they sought to legislate on and thereby over-rule) on the statute laws of the British Colonies of Australia/New South Wales which at that time included: Tasmania (hived off later in 1823); Western Australia (1827); South Australia (formed in the 1830s); New Zealand (1840); Victoria (1851); Queensland (1859). (Northern Territory was part of NSW in 1820s).
https://www.rootschat.com/forum/index.php?topic=648372.0NSW marriage Acts that were repealed by NSW marriage Act of 1855, effective from commencement of civil registration 1 March 1856:
6 Geo IV no. 21 passed 1 November 1825
5 William IV no. 2 passed 4 July 1834
7 William IV no. 6, passed 5 August 1836
2 Vic No. 13, passed 29 August 1838
3 Vic No. 7 passed 5th September 1839
3 Vic No. 23 passed 19th November 1839
4 Vic No. 14 passed 23 September 1840.
1856
https://www.rootschat.com/forum/index.php?topic=660501.0 noting it includes the following link:
http://www8.austlii.edu.au/cgi-bin/viewdb//au/legis/nsw/num_act/ma1855n30112/ NSW Marriage Act 1855
…
14
Every Marriage celebrated in this Colony before the commencement of this Act by any Minister of Religion or person ordinarily officiating as such shall be deemed to have been from the time of the celebration thereof a perfectly legal and valid Marriage (not withstanding any non-compliance with forms or other irregularity attending the celebration) to all intents and purposes.
15.
Provided that nothing in the previous section or in the fifth section of this Act shall legalize any Marriage declare or made (or which shall hereafter be declare or made) invalid by any competent Court or by Act or Council nor any Marriage where either party thereto had another wife or husband then living nor any Marriage which would have been or would be void but for those sections by reason of relationship kindred or alliance or of fraud or incapacity to contract Marriage nor any Marriage where (the same being at the time of its celebration invalid) either of the parties thereto shall afterward and before the passing of this Act have intermarried with some other person.
In Victoria in 1906 cousins can marry .... see
https://trove.nla.gov.au/newspaper/article/222626752 Weekly Times 10 Sept 1906 and
https://trove.nla.gov.au/newspaper/article/222532696 Weekly Times 29 Sept 1906, Addie asks 'Can first cousins legally marry', and the response given is 'Yes'.
However, the Catholic Advocate of 23 March 1912 had a different view - the question was slightly different too. 'Can first cousins marry in the Catholic Church?'
https://trove.nla.gov.au/newspaper/article/258455746 And again in 1916, it is confirmed that first cousins can marry
https://trove.nla.gov.au/newspaper/article/132719362 and from 1930 in Western Australia people were still confused about first cousins marrying
https://trove.nla.gov.au/newspaper/article/38520012 But basically, after decades of enjoying researching my own ancestors, and having a very helpful pool of older relatives, including retired : Clergy, archivists, senior NSW bdm officers, ... I am not aware of any statute requirements banning first cousins marrying in any of the colonies or states that form the Commonwealth of Australia.
https://www.churchofengland.org/prayer-and-worship/worship-texts-and-resources/book-common-prayer/table-kindred-and-affinity My C of E 'The Book of Common Prayer, Hymns A & M' at page 384 has a similar table to the one in that link 'Wherein whososever are related are forbidden in scripture and our laws to marry, so no mention of first cousins being forbidden to marry.
On a lighter note, Hymn No. 707 is the National Anthem .... God Save the King. - and of course it is referring to George VI.
Add to be pedantically correct, the table in my Book of Common Prayer is headed
A Table of Kindred and AffinityJM