A South Sydney junior,[2] at the end of the 1949 NSWRFL season Hammerton played in his first grand final at hooker for South Sydney who lost to St. George. At the end of the 1950 season Hammerton played in the grand final at hooker for South Sydney who defeated Western Suburbs. In 1951 Hammerton played in the grand final at hooker for South Sydney, scoring a try in their victory over Manly-Warringah. In 1951 Hammerton was selected to represent Australia, becoming Kangaroo No. 288.[3] He played a sole test match, a 23โ11 victory over the touring French team.
In the 1952 NSWRFL season Hammerton played in the grand final at hooker for South Sydney who lost to Western Suburbs. At the end of the 1953 NSWRFL season Hammerton played in the grand final at hooker for South Sydney, scoring a try in their victory over St. George. In season 1954 Hammerton played in the grand final at hooker for South Sydney who defeated Newtown. At the end of the 1955 NSWRFL season Hammerton played in the grand final at hooker for South Sydney who again defeated Newtown. South Sydney came within one match of the 1957 NSWRFL season's grand final, however Hammerton was dropped from the team for the qualifier in favour of 22-year-old Brian Murray.[4] Souths lost the match. The following season was Hammerton's last in first grade.[5]
Post-playing career
Hammerton was appointed a New South Wales selector in the 1970 pre-season.[6] In 1972 Hammerton, who was already a New South Wales selector, won a position on the Australian Rugby League selection committee.[7] A decade later he was still a national selector.[8] He was replaced as chairman of Australian selectors by Don Furner in the 1989 pre-season.[9]