He was best known for being part of the musical trio Rod, Jane and Freddy which appeared in children's programming in the 1980s and 1990s.

[1] In his early career, Marks appeared on stage in productions such as The Lion in Winter and as part of Dundee Repertory Theatre.

[1] In 1980, Marks was hired to join the cast of Rainbow after Roger Walker left the show.

Rod, Jane and Freddy aired its first episode in January 1981, and in total seven series were broadcast.

The trio continued to appear in Rainbow until 1989, and the following year Thames Television lost the ITV franchise.