Gilbert Allen McKenzie, known as Alan, was born at Invercargill on 27 May 1915. The second son of Mary Anna Reed and her husband, David McKenzie, he was born without arms.
The McKenzie family lived in the small mining town of Nightcaps in western Southland; David owned the New Brighton mine in nearby Moretown. He died in a mining accident on 19 December 1918 and the mine was sold by his estate soon after. Mary McKenzie, widowed with two young sons, probably took in boarders but little else is known about the family's financial circumstances.
Alan McKenzie survived the 1918 influenza epidemic and was a cheerful, active child. He seems to have been encouraged to be as independent as possible from an early age. Although physically incapable of activities such as dressing himself, McKenzie displayed a determination to concentrate on his abilities. He became skilled at using his feet: he could feed himself, and at the Nightcaps school he learned to write with a pencil held between the toes of his right foot, or in his mouth. He worked at a low square table, one of the few concessions he allowed to be made for him. His attitude earned McKenzie the respect of his community and he enjoyed being involved in local events. He participated in school sports and games and became the mascot of both the Nightcaps women's hockey team and the football team.
As he became more proficient at using his feet Alan McKenzie discovered a talent for drawing and sketching. Samples of his clear and legible writing and his drawings were taken around Southland schools, and he was encouraged to develop his talents and to display his work. He attended Southland Technical College for three years, concentrating on art. A keen student, McKenzie experimented with a variety of art forms including carving and pottery, but he became most accomplished at pencil drawing, tempera painting, watercolour and linocuts. His pen-and-ink sketches in particular were noted for their intricate detail.
McKenzie also had an interest in music. He came up with a method of playing the piano using a device held between his toes and would sing along in his pleasant baritone voice. He studied singing in Invercargill under Hugh Kennedy Black and began to make public appearances at concerts around the district. Slim and dark-haired, McKenzie was a gifted entertainer, with a talent for impersonations, and his performances at local concerts included imitations of well-known singers of the time. He also developed the idea of doing full-colour lightning sketches of a scene appropriate to the song he was singing. His public performances were always well received, and he was well known throughout Southland.
Alan McKenzie attended King Edward Technical College and the Dunedin School of Art for two years, and while nothing is known of his personal life during this period, he continued his study of music in Dunedin under Ernest Drake. He was able to earn some money from his art and performances but it is unclear whether he was fully self-supporting. Some of his work was used in advertisements and he was apparently working as a signwriter in 1935 in Invercargill. For at least some of his adult years he received an invalid's pension.
In a bid to gain financial independence, McKenzie moved to Wellington for the New Zealand Centennial Exhibition in 1940. He set up his own stall where he entertained the public with his impersonations, sketches and painting. He sold his art works and a postcard he had made featuring a signed photograph of himself painting in tempera with a brush held between his toes. He hoped to join the New Zealand army as an entertainer after the exhibition, but he became ill with cystitis and returned to his mother's home in Nightcaps. He died on 26 May 1941; he had never married.