Byrnes was born into a Protestant Anglo-Irish family which migrated to Sydney when Byrnes was 2 years old. His father served with the Rum corps and with other regiments garrisoned in NSW. Byrnes had little formal education but became a successful carpenter and builder. Together with his brother William he invested in steam-powered cotton, wool and flour mills and pioneered steam ferry transport on the Parramatta River. He later invested in a number of colonial banks and insurance companies. Byrnes was a leading Methodist layman and was involved with a number of charities in Parramatta including the District Hospital and the Benevolent Society.
Colonial Parliament
Prior to the establishment of responsible self-government, Byrnes was elected to the semi-elected New South WalesLegislative Council in March 1850. He represented the electorate of County Cumberland but resigned after 15 months. Following the granting of self-government, Byrnes was elected to the first Legislative Assembly as one of the three members for the seat of Cumberland. Although failing to be elected at the general election of 1856, he was subsequently successful at an 1857 by-election caused by the retirement of William Manning due to ill-health. At the 1858 colonial election he was elected to the two-member seat of Parramatta. He was subsequently the first member elected to the seat at the 1859 election but at the 1860 election he gained second place behind a newcomer John Lackey. While still successful, Byrnes took offence at being placed second and used his declaration of poll speech to upbraid the voters. He resigned from the seat before parliament met. Following his resignation, in 1861 he was one of 21 men that Premier Charles Cowper appointed in an attempt to stack the Legislative Council, however there was a mass walk-out from sitting members which meant that the council was unable to sit before it was prorogued and Byrnes and the others were unable to take their seat. At the next election in 1864–65 Byrnes was again the first member elected for Parramatta and he retained the seat until he was defeated at the 1872 election. Subsequent attempts to re-gain public office were unsuccessful.
Byrnes married Ruth Barber in 1826 and together they had five sons and a daughter. He remarried in 1852 to Ann Harris and they had a daughter. His youngest son, Charles, took over the woollen mill and was also a member of the Legislative Assembly as the member for Parramatta at various times between 1874 and 1882. His brother William was a member of the Legislative Council between 1858 and 1891.
