Peter Matthew Mills was the son of Matthew Mills.¹ Peter was born in 1743 in St Kitts, and he died in England in 1792.²

Peter's father had been murdered after a quarrel in 1752, meaning Peter inherited various estates when he left school and matriculated at Christ's in 1760.² In 1762, he married Catherine Hamilton, who was probably also born in St Kitts.²

Peter's father, Matthew, whom the Legacies of British slavery project describes as a 'slave-owner on St Kitts', left his 'real estate, all [his] plantations & negros' to Peter in his will.³ ⁴ Peter also inherited plantations in St Kitts from his maternal grandfather, Peter Soulegre.⁵

Matthew had inherited a London sugar house, as well as unspecified property in 'Nevis & St. Kitts', from his uncle in 1747, five years before his death.⁴ ⁶ The sugar house was acquired by two of Matthew's relatives, John and Thomas Mills, after his death.⁶

Peter is recorded as the owner of the Bottom and Carpoons estate and the Olivees plantation, both in St Kitts.² Peter sold the Olivees plantation to the Akers family for £16,800 in 1782.⁷

In 1817, the Bottom and Carpoons estate was registered as part of Peter's estate, held in trust, along with 171 enslaved people there.⁸ Peter's younger son, Charles Andrew Mills, who had been bequeathed £10,000 in his father's will, made a claim for compensation for enslaved people on the estate in 1835.​⁹ ¹⁰ Charles and another trustee received a total of £2929 11s 4d for 171 enslaved people on the estate.¹⁰

George Galway Mills, Peter's eldest son, received the majority of his property on St Kitts in Peter's will.​⁹ He later served three brief stints in the House of Commons in the 1800s and 1810s, during which time he repeatedly moved abroad, blighted by debt (which amounted to £43,000 in early 1807).¹¹ ¹² He died by suicide in Australia in 1828.¹¹

Both Peter and his father owned enslaved people and plantations in St Kitts, and profited directly from doing so. It is probable that Peter's education at Westminster and then Christ's was funded from his father's estate. The Bottom and Carpoons estate was evidently maintained in trust after Peter's death, meaning his son Charles could also benefit from enslavement, including through the claim for compensation for 171 enslaved people in 1835.