Background
Mark Rexford Sutherland was born in Orange, California, the third of four boys. In the early fifties his family moved north to Los Angeles. According to Disney press releases, he had worked with his two older brothers in a dance act, and had appeared in television and films prior to auditioning for the show. He wanted to be a disc jockey when he grew up; his hobbies were Little League baseball (he played catcher), football, swimming, and horseback riding.
Performance
Mark was a fair dancer, and could sing well enough in groups, but never did a solo performance that I can recall. He did seem to have a problem maintaining focus on-camera, possibly due to light sensitivity. The powerful arc lights that shone in the performers faces seemed to trigger a reaction in Mark, who can often be seen blinking and looking away from the camera.
One of the first sequences filmed for the show in May 1955 was the Talent Round-Up introductory song and dance. For some reason Mark wound up in this instead of Lonnie Burr, who appeared in Roll Call the other four days of the week. Because the Roll Call segments were only filmed once (unlike the Alma Mater), Mark thus appeared every Friday with the Red Team throughout the show's first season. Mark's regular assignment was the Blue Team, for Guest Star Day and Circus Day.
During the fencing match on Talent Round-Up Day between brothers Bobby and
Johnny Crawford, Mark seemed like he wanted to jump into the bout. Mark himself was a Talent Round-Up Day winner as a disc jockey, dishing up the palaver in between songs by
Darlene Gillespie. (Thanks to Rick from Dallas for confirming this).
Like the other Mouseketeers, Mark probably took part in the Disneyland Circus. This started after the first season filming wrapped up in early November 1955, and continued through early January 1956. At that point the majority of Mouseketeers, including Mark, were let go as their contract options expired.
Aftermath
Little is known about Mark's post-Mickey Mouse Club life. He doesn't appear to have continued in show business, and for many years his whereabouts were unknown to the Disney Studio and the Screen Actors Guild. He did contact the studio just before the televised 25th Anniversary Show in 1980, but either declined to take part or could not work it into his schedule. He is the only original Mouseketeer to have neither taken part in post-show activities, nor to provide a public update on his life and career.
Coincidently, Disney Radio hired a young disc jockey called "Just Plain Mark" in the 1990's, who was also named Mark Sutherland.