Often overlooked by the filmgoing audience at large, the orchestrator is something of an unsung hero in the world of cinematic music. In spite of this, Williams has acknowledged Spencer's invaluable contribution to these legendary scores in interviews and documentaries. The orchestrator is given a condensed musical sketch to expand and notate for the full studio orchestra. Although Williams' sketches are highly detailed and leave little room for artistic license on the part of the orchestrator, the process requires a comprehensive knowledge of each instrument in the orchestra and a mastery of textural and coloristic craft, and is crucial to the timely completion of the score. Spencer's work is considered to be some of the best ever recorded for film, and his reputation among Hollywood composers and orchestrators remains without peer in the industry today.
Since Spencer's passing in 1992, Williams has worked frequently with orchestrators John Neufeld and Conrad Pope, as well as others.