Van Diemen's Land: Polity Style: 1804-1825

26 Jan 1788	part of Australia known as the territory of New South Wales is declared a possession of the King of Great Britain after the arrival and landing of the troops assigned to establish a penal colony at Sydney Cove (New South Wales Historical Records, 2:543; Governor Phillip's Voyage, p. 58)
7 Feb 1788	New South Wales, including the territory of Van Diemen's Land, is placed under the administration of a Governor-in-Chief, in accordance with a commission issued by command of the King of Great Britain on 2 Apr 1787 which was read and published at Sydney Cove on 7 Feb 1788 (New South Wales Historical Records, 2:393, 2:399; Governor Philip's Voyage, p. 64) [1]
17 Nov 1803	a settlement and settlements to be formed on the southern coast of New South Wales are placed under the administration of a Lieutenant Governor, in accordance with a commission issued by command of the King of the United Kingdom of Great Britain and Ireland on 14 Jan 1803 which was read and published at Port Phillip on 17 Nov 1803 (Australia Historical Records, Series 3, 1:57; Port Phillip Historical Records, p. 145)
16 Feb 1804	Lieutenant Governor Collins lands on the island of Van Diemen's Land (Port Phillip Historical Records, p. 167)
3 Dec 1825	the island of Van Diemen's Land and adjacent territories are separated from New South Wales, and constituted and erected into a separate colony on 3 Dec 1825, the date of issuance of the proclamation in Hobart, publishing an Order in Council issued on 14 Jun 1825 under an act passed by the Parliament of the United Kingdom (House of Commons on 11 Jul 1823, House of Lords on 16 Jul 1823 with amendments, House of Commons agreed on amendments on 18 Jul 1823, received royal assent on 19 Jul 1823) (UK Statutes, 1823-1824, pp. 505-515; Hobart Gazette, No. 501, 10 Dec 1825, p. 1; Australia Historical Records, Series 3, 4:304-306) [2]

Van Diemen's Land was not explicitly mentioned in the royal commission appointing the first Governor-in-Chief, but the boundaries of New South Wales was claimed to have included a territory extending to "South Cape" in the latitude 42° 39', roughly covering the present Island of Tasmania, although its separate position from the continent was not known at the time.
Full title: An Act to provide, until the first day of July, One thousand eight hundred and twenty Seven, and until the End of the next Session of Parliament, for the better Administration of Justice in New South Wales and Van Diemen’s Land, and for the more effectual Government thereof; and for other Purposes relating thereto.