Cairns attended Sunbury State School and later Northcote High School, where he completed his Leaving Certificate. Though life during the Depression was difficult with his mother having to work to provide for the family, and with himself having to make a three-hour daily commute by train, he was a good student, making his name at Northcote High School due to entering the school's broad jump championship and winning it easily with a jump of twenty feet and two inches, his competitors producing jumps of sixteen to seventeen feet.