Born and raised in Coventry, England, St.John received his B.A. (with honors) in French from the University of Liverpool.

He lived and worked in France for two years before coming to the U.S. in 1986 to attend graduate school at the University of Georgia (UGA) in Athens. He worked as a teaching assistant while pursuing his master's degree in French and taught introductory level French classes.

After completing his M.A. he was accepted into the Ph.D. program in comparative literature at UGA where he taught world literature survey classes.

St.John started in public radio at WUGA-FM, the Georgia Public Broadcasting (GPB) affiliate on the UGA campus, as a part-time weekend classical announcer.

In the spring of 1995, he was asked to host Night Music, WUGA's weeknight classical program that aired on all 15 GPB stations around Georgia. As a result of this exposure he was offered a part-time job at GPB headquarters in Atlanta and moved away from Athens leaving behind an unfinished Ph.D. dissertation.

He was hired full-time at GPB as a cultural affairs producer in 1997; he continued to host classical music on the network but also began to produce arts pieces for GPB's weekly news magazine. He also developed Cover to Cover, a monthly call-in book show focusing on Georgia authors.

He was the GPB network host for NPR's All Things Considered for a number of years before moving to Morning Edition which he hosted for eight years.

In 2001 he was promoted to Radio Program Manager, supervising all GPB network programming, and in 2005 he was asked to become Radio Manager, reporting to the Executive Director, with responsibility for GPB radio operations around the state.

Welcoming the chance to work at a major market station, St.John joined KUHF as Program Director for KUHF-Classical in March 2008, and now acts as Program Director for Classical 91.7FM. In addition to his role as host and executive producer of The Front Row (Classical 91.7's daily arts magazine), he supervises the classical announcing staff and the audio engineers responsible for the station's concert recordings around town, including the Houston Symphony.