Kirton attended Victoria University of Wellington for his agricultural intermediate before transferring to Massey University where he completed a BAgrSc (1956) and an MAgSc (1958). For his MAgSc he received First Class Honours in Sheep and Dairy Husbandry. While studying at Massey he received a number of prizes including the Lord Bledisloe Prize, the George Terry Memorial Scholarship, the Senior Scholarship in Agriculture (declined), a NZ Wool Board Scholarship and a Shell Oil Company Scholarship.
He then spent some time on the Massey staff working for the Sheep husbandry Department. He received a MacMillan Brown Agriculture Research Scholarship and a Fulbright Travel Grant which enabled him to enroll for PhD studies at Michigan State University. He studied under Professor A M Pearson and completed a doctorate in Food Science in 1962. Before leaving the USA Kirton was elected to membership of Sigma Xi, the PhD honorary fraternity.
Upon his return from the USA in 1963 Kirton was employed by the Ministry of Agriculture and Fisheries in the Meat Group at the Ruakura Animal Research Station. In 1966 he was promoted to lead the Meat Group and remained in this position for over 30 years until he retired in 1999.
Kirton drove the need for a research abattoir and then oversaw the planning and construction of Ruakura Research Abattoir. The abattoir remains to this day a major facility for undertaking production and processing research directly aligned to the New Zealand meat industry. Kirton took an interest in animal welfare and chaired the Ruakura Animal Ethics Committee for 10 years from 1988–1997. He was at first met with opposition from parts of the industry but, as a result of his hard work, those attitudes soon faded.
Kirton dispelled a number of myths that prevailed in the industry, showing that—
Kirton's leadership was influential in the number of farmers choosing to no longer castrate their rams or even remove the tails, so improving meat yield without compromising meat quality, and improving animal welfare.
Kirton produced over 290 publications for the Meat Science scientific literature, 212 of which he was senior author, and contributed 9 chapters to a number of books at the forefront of the industry. He was a committee member, secretary-treasurer, vice-president, and an honorary life member of the New Zealand Society of Animal Production (1975), a committee member, vice-president, president (1969–70, 1970–71) and (1991–92, 1992–93) of the New Zealand Association of Scientists, and a committee member and a president (1980–81) of the Waikato Section of the New Zealand Institute of Agricultural Science and a council member and president (1987–88) of the national body.