He was a "citizen of the world", (His citizenship was listed as French, American and Australian) who played an important role in the development of commerce and banking in the British Colony of New South Wales.
His other descendants include: Sarah Melanie de Mestre (1877–1961) who distinguished herself as a nurse in France and Flanders in World War I, and whose decorations included the Royal Red Cross which was presented to her at Buckingham Palace by King George V on 3 June 1918 (the King's birthday);[1] Roy de Maistre (1894–1968), a successful Australian artist; Guboo Ted Thomas[2] (1909–2002) a prominent Aboriginal leader, and the last initiated tribal elder on the South Coast of New South Wales; Margaret Augusta de Mestre (1915–1942), a nurse who was killed in action on a hospital ship on 26 February 1942 in the bombing of Darwin during World War II;[3] Neville de Mestre[4] (c.1938- ), an eminent Australian mathematician and author, Emeritus Professor of Maths at Bond University, and who has held the titles of World Iron Man champion in the 60-64 age group, and Australian and World Masters surfing champion in the over-65 group for body surfing;[5][6] and Lloyd Nolan Hornsby[7] (1947- ), a prominent Aboriginal artist.
It is therefore also not true that Prosper is the son of a liaison between Julie de St Laurent and Edward Duke of Kent, the father of Queen Victoria.
In this letter he made a statement that claimed he had been born in 1793 while his parents had been fleeing the French Revolution on a British ship bound for Martinique.
Chief Justice (Sir) Francis Forbes of the Supreme Court of New South Wales, after various letters and evidence (including Prosper's letter to the Collector and Comptroller of Customs), ruled that because Prosper had been born on the high seas in a British ship he was a British subject, and therefore his application must succeed.
In March 1791 André Charles' regiment was transferred under the royalist new Governor-General Behague to the island of Martinique in the French Caribbean, regarded politically as part of France.
His activities were greater during the siege and his multiple assets were to be at the same time director of the artillery, captain of the gun markers and the bombardier.
A year later in March 1795, Prosper's mother Helene married an officer of the invading British Army, Captain James "Jean" Armstrong (1769-aft.1836) of the 6th (1st Warwickshire) Regiment of Foot.
[15] In 1802, when Prosper joined her, Prosper's mother was living in Philadelphia as a single mother and widow,[16] In late 1803 she married Joseph Coulon (1763–1815), a Frenchman and naturalised American citizen (Philadelphia 1798), an import merchant, who had connections with France, with Pondicherry in India, with Mauritius, and possibly also with the Caribbean.
Using his overseas trade connections through fellow American citizens in China, he began to import goods, including tea.
Prosper's commercial trading advantage, from his importation of goods from China, was seen by other Sydney merchants as unfair and caused resentment.
In 1820 Edward Eagar brought a qui tam action against the American merchant Prosper de Mestre.
If successful, he would have bankrupted Prosper as his estates would have been forfeited: two-thirds going to the Crown (the King and Governor); and the remainder to the informer, Eagar.
Justice Barron Field of the Supreme Court of New South Wales agreed with Prosper's argument, and Eagar's action failed.
One of those of like mind that Eagar collaborated with was the child of a convict, and barrister, William Charles Wentworth, who returned to Sydney from overseas in 1823.
Mary Ann was a good catch for de Mestre, with her stepfather Simeon Lord's connections being invaluable to Prosper's business dealings.
The Act was passed on 30 August 1825, and published in the Sydney Gazette and New South Wales Advertiser by the Governor Sir Thomas Brisbane on 1 September.
This colonial naturalisation declared Prosper to be a "Natural-born Subject of Great Britain, and to be entitled to all the Rights, Privileges, and Advantages, which are conferred on Foreign Protestants".
Wentworth, who for political and professional reasons would not have wanted the court to need to consider the legality of naturalisation act passed by the Legislative Council of New South Wales in 1825, again advised Prosper during the 1830 action.
It is of no co-incidence that, in 1790 shortly before his parents arrived at the penal settlement of Norfolk Island, Wentworth had been born at sea on a British ship.
Prosper had been born in France before his family had moved to Martinique, where his soldier father had been killed in action against the British in March 1794.
Prosper's commercial interests in the Colony of New South Wales were mainly in shipping and whaling, but he also became active in wider commerce.
His first property purchase was in 1821 in George Street, Sydney, an allotment that had been received by his brother-in-law John Henry Black as his dower, and that was next door to a portion of land that his wife Mary Ann had also received as her dower[20] on her marriage, and had been held in trust by her stepfather Simeon Lord from an original land lease given to her father Captain John Black.
In 1824 (prior to his 1825 naturalisation) Prosper De Mestre was first promised a land grant by Governor Thomas Brisbane.
[21] The homestead Mill Bank House which still stands in Millbank Road, was probably erected at this time, and a village named Terara soon began to develop.
His house in Liverpool St, and its "elegant Household Furniture", was sold by auction on 16 May 1844, and the family was moved briefly to Petersham and then onto Terara, which Prosper had initially developed as a hobby farm.