[6] Having experienced life as a woman in Victorian society, single, married and widowed, Mary became concerned with what today would be called a feminist issue.

Remembering that colonies in Australia were largely governed by English law, prior to the English 1887 Married Woman's Property Act (which was a rallying point for many first-wave feminists in the late nineteenth century, and was only passed after years of intense political lobbying by dedicated women[7]) a married woman could own no property, and was the chattel of her husband.

After being transported to Sydney as a teenage convict, Mary became the unmarried partner of Captain John Black (1778–1802) the privateer (state-sanctioned pirate), whaler, ship's captain, navigator and master mariner who named King Island; and later the wife of Simeon Lord (1771–1840) a wealthy entrepreneurial emancipist merchant and magistrate.

On 21 March 1796, at the age of 17, Mary, who also used her mother’s name as an alias, was sentenced at the Warwickshire Assizes to seven years' transportation to New South Wales for theft.

[11] As Mary stayed in Sydney, it can only be assumed that she was initially chosen by one of the men in the "cattle auction" on board the deck of the Britannia II.

In August 1798, when they were both 19 years old, Mary met John Black, a ship's officer who had survived the mutiny on the Lady Shore in 1797, and who that month had arrived in Sydney on board the Indispensable.

Mary, however, was often "keeping the home fires burning" as John was away for months at a time either whaling or otherwise working his trade as a ship's captain.

This was because Mary "living on the lease of Mr. Black; and owning 7 sheep, 4 pigs and 3 goats" had been able to meet a level of self-sufficiency, something the government greatly encouraged in an effort to cut costs.

[citation needed] On 7 September 1801, Governor Philip Gidley King granted Mary Hyde an Absolute Pardon, eighteen months before her sentence would have expired.

[citation needed] Back in January 1801, when John Black had returned to Sydney from one of his long voyages, Mary Hyde became pregnant with their second child.

He was the former convict, and one of early Sydney's great characters, businessman Simeon Lord, who in addition to becoming a magistrate also happened to be one of the most litigious men in the colony.

Simeon Lord knew both Mary and her previous partner through trading dealings involving Black’s ships whose goods had been stored in his warehouse.

With investments in Lord's name, they also became one of the richest couples in the Colony of New South Wales, with only six Sydney residents having greater landholdings.

After her husband's death, in addition to managing large livestock and landholdings, Mary continued the manufacturing business in the factory at Botany.

In order to gain reasonable compensation for this resumption the then 76-year-old Mary took the Commissioners of the City of Sydney to the Supreme Court of New South Wales.

Mr. Justice Dickinson ruled that plaintiff, having no mill that was deprived of its motive power, was not entitled to damages to the use of the water, but that this could only be decided by a decision by the full court, on appeal.

Mr. Justice Dickinson ruled that the use of the water for possible wool washing was incompatible with the terms of the original land grant, but that this could only be decided by a decision by the full court, on appeal.

Held over two days, Mary's case included the special jury of twelve travelling from the court house to Botany to view the land that had been resumed.

As in the previous cases, whether Mary had been entitled to the undisturbed use of the water was something that Mr. Justice Dickinson ruled could only be decided by a decision by the full court, on appeal.

Lord Kingsdown (Judge of the Admiralty Court), Lord Justice Knight Bruce, Sir Edward Ryan, and Sir John Taylor Coleridge had decided, despite contrary arguments from the defendants, that Mary had been entitled to the undisturbed use of the water on her land that had been resumed, and that she was entitled to the extra £7,200 compensation.

Due to the prohibitive circumstances under which Australian women were living legally and socially, and that for anyone living in Australia prior to or during the Victorian era it was expensive and geographically difficult to appeal a case in England, Mary is perhaps the first, and possibly only, female and/or female convict, to have taken a legal case from New South Wales to the Privy Council.

One of her sons-in-law was another successful merchant in Sydney, Prosper de Mestre (1789–1844) who married her daughter Mary Ann Black (1801–1861).

An ambrotype photographic portrait of Mary Hyde (Mrs Simeon Lord), in its case, and taken sometime in the period 1845–1860, is in the collection of the Powerhouse Museum in Sydney.