[1] As with many of the other great orchestrators, Walker served a long apprenticeship with Max Dreyfus at Chappell Music's arranging department starting in the 1930s,[2] until he finally went out in business for himself in the early 1950s setting up office in New York City.
With this in mind, he set up Music Theatre International in partnership with Frank Loesser, which has managed the subsidiary rights of many shows since the mid-1950s.
"[8] Nevertheless, Sondheim was so pleased with Walker's work that a year after the show closed, he sent the orchestrator a note "to thank you once more for the marvelous job you did.
Other composers who frequently worked with Walker were Richard Rodgers (Carousel, By Jupiter, Me and Juliet), Cole Porter (Leave It to Me!, Something for the Boys, Silk Stockings) and Jerry Bock (Fiddler on the Roof, She Loves Me, The Rothschilds).
His orchestrations for Frank Loesser's The Most Happy Fella, which had never been filmed, were heard in the 1980 production of the play telecast on Great Performances.
[citation needed] Walker also did the arrangements for Fred Waring's Pennsylvanians and was the conductor for the television program Your Hit Parade.