Barnett and five other gold medal winning Wallabies joined the Newtown club in Sydney in 1910 where he played the next six seasons. He was a member of the premiership winning Newtown side in 1910. He was selected in both Ashes Tests against Great Britain in 1910 when Australia hosted the tourists.
Barnett died on 2 October 1918, aged 38 at the Parramatta District Hospital from the effects of meningitis after a three-week battle with pneumonia. He was survived by his wife and two daughters. He was buried at Rookwood Cemetery on 4 October 1918. As a tribute to "Towser" Barnett, a fund was set up by "the Referee" newspaper to raise money for his widow and family. By the November the fund had raised over £64, many donations were made up by his first grade rugby mates, at a time when spare money was often in short supply.
^ abc"Funeral Notices". The Sydney Morning Herald. NSW, Australia. 4 October 1918. p. 5. Retrieved 13 August 2010.
^ abThe birthyear of John Thomas Barnett is erroneously cited as 1886 by databaseSports.com. In addition it is cited as 1881 by ESPN's Scrum.com database, which is also in error. The birth year is registered in the NSW Registry of Births, Deaths, and Marriages as 1880 - Registration #: 12032/1880.