Glynn was born in Gort, County Galway, Ireland and educated at the French College, Blackrock and Trinity College, Dublin. Glynn graduated with a BA and LLB, and was the medallist for Oratory at the Law Students Debating Society of Ireland in 1880. The same year saw Glynn immigrate to Australia. Glynn was admitted to the Victorian bar. His time in Victoria was not a success and in 1882 he moved to Kapunda, South Australia to open a branch of an Adelaide-based law firm. His success in Kapunda allowed him to open his own law firm in Adelaide and involve himself in the political sphere. He also edited for some time the Kapunda Herald.
Glynn served as president of the South Australian branch of the Irish National League and helped found the South Australian Land Nationalisation Society. His community profile assisted him in his election to the South Australian House of Assembly as the member for Light in 1887. As an advocate of free trade, Glynn was considered a conservative but his support of progressive issues like female suffrage and land nationalisation isolated him from his conservative colleagues. Glynn was defeated at the 1890 election and stood unsuccessfully for Light again at the 1893 election but returned to South Australian colonial politics in 1895 as the member for North Adelaide. With this victory, he became the first person in Australia to be elected under adult suffrage. While he was defeated a year later at the 1896 election, he returned to parliament in a by-election for the seat of North Adelaide in 1897. Glynn briefly served as Attorney-General of South Australia in 1899 and remained in parliament until 1901.
Constitutional convention
Glynn was a member of the Convention that framed the Australian Commonwealth constitution in 1897–98. He was regarded as one of the ablest authorities in Australia on constitutional law. He made major contributions to Murray Riverwater rights, free trade, standardising rail gauges and universal suffrage. He also contributed a reference to God in the preamble to the Australian Constitution, and helped found the Free Trade Party, one of the major parties of Australian politics in the early 20th century.
Federal politics
First federal election
In the lead up to the inaugural federal election, Glynn acted as the informal deputy leader of the Free Trade Party and managed the Free Trade election campaigns in South Australia and Western Australia, while Free Trade leader George Reid oversaw the rest of Australia. As a result, Glynn was not only comfortably elected to the single statewide Division of South Australia but, together with Reid, he is said to have "created Australia's first national political campaign."
Government minister
At the 1903 election, the statewide constituency was abolished and Glynn was returned unopposed in the Division of Angas. He was re-elected on five further occasions, and was unopposed at three consecutive elections. Despite his ties with Reid, Glynn was not offered a place in the Reid Government. He joined the new Liberal Party after the 1909 "fusion" with the Protectionists, and subsequently served as Attorney-General under Alfred Deakin from 1909 to 1910. He returned to ministerial office in 1913 as Minister for External Affairs in the Cook Government, holding the position until the government's defeat at the 1914 election. In 1917, the Liberals merged with Prime Minister Billy Hughes' National Labor Party, forming the Nationalist Party. Glynn's final ministerial post was as Minister for Home and Territories from 1917 until his defeat at the 1919 election. In that capacity he handled the Darwin rebellion of 1918.
Later life
Glynn retired from politics in 1919, and died at North Adelaide in 1931. He married Abigail Dynon, who predeceased him, and was survived by two sons and four daughters. He was a fine Shakespearian scholar; several of his literary papers were published, as were also various legal and political pamphlets.
