John Mayo was born in 1799 and lived in Coleford where he worked as a hairdresser. On 2 August 1817, at the age of 17, he was condemned to death for entering a house in St Briavels and stealing an ebony flute valued at 20 shillings the property of James Davies. However, he was reprieved and no other sentence was imposed having spent about six months on remand.
On 31 Aug 1818, he was sentenced to be transported for seven years for breaking into a house in Cheltenham and stealing a silver-plated urn valued at 5 shillings with Daniel Powell, aged 27 from Trelleck, who was also transported for seven years. He was transferred to the hulk, the Justitia and then to the Baring which set sail for New South Wales on 27 January 1819 and arrived on 26 June 1819.
In 1804, following the uprising at Castle Hill, a permanent settlement was established at Newcastle to house convicts who re-offended in the Colony. Until it closed in 1822 the Newcastle settlement functioned principally as a place of secondary punishment for convicts sentenced by the courts for offences while serving their original (primary) sentence in the Colony. In November 1820, Mayo was convicted of theft and sent to Newcastle for 14 years.
John Mayo died on 24 June 1860 aged 64.