 Formerly director of music and organist at Riverside Church in New York City (1983–1992) and Shadyside Presbyterian Church in Pittsburgh, Pennsylvania (1992–2005), Walker has a Doctor of Musical Arts degree from Stanford University and is a past President of the American Guild of Organists.He was named "Minister of Music Emeritus" by Brown Memorial in 2012 and continues to perform there occasionally.Other previous organists include the celebrated virtuoso Virgil Fox, who gained considerable fame as a concert performer and recording artist while at Brown Memorial early in his career, from 1936 to 1946.