Robert Lethbridge represented Australia at the 1974 Commonwealth Games in New Zealand, winning a Bronze Medal in Decathlon.
His success in athletics began in primary school, when he won the Victorian Primary Schools’ Championship in Triple Jump, setting a new record for the event. His success continued throughout his secondary schooling, culminating in him becoming Victorian Under 17 Champion in Long Jump, and Under 19 Champion in Javelin and Pentathlon.
Whilst studying at the University of Melbourne, Robert continued to compete in athletics, setting Victorian and Australian records in Under 19 Pentathlon and Open Decathlon. In 1975 Robert was placed first in the Australian Championships in the Open Decathlon, and in 1984 and 1985 was Victorian Champion in Javelin.