Grammar Schools Old Boys Rugby Club was originally formed in 1914 under the name Auckland Grammar School Old Boys Club. In the 1920’s the club agreed to admit former pupils of Mt Albert Grammar which had been founded in 1922, and by 1927 Takapuna Grammar’s Old Boys also gained admittance. It meant a change in the design of the original club badge, which had comprised the single heraldic lion of AGS. The new badge contained three similar lions. And on March 15, 1932, the name of the club was changed to Grammar Old Boys.
In 1996 Grammar combined with Carlton Rugby Club to become Grammar Carlton Rugby Club. Carlton Rugby Club had been formed in 1982 when Grafton, established in 1873 amalgamated with Cornwall, established in 1922.
In 2014, Grammar Carlton combined with Teachers Eastern to form Grammar TEC (where TEC stands for Teachers Eastern Carlton).