Ledger was noted for compositions and arrangements, especially for choir. After succeeding David Willcocks as Director at King's, he wrote a number of new descants and arrangements of Christmas carols, and settings of popular texts such as "Adam lay ybounden" and "A Spotless Rose". His arrangement of "This joyful Eastertide" for mixed voices and organ has been widely performed and broadcast. Many of his works and editions were published by Oxford University Press, Encore Publications, the Lorenz Corporation (USA), and the Royal School of Church Music. His Requiem "A Thanksgiving for Life" is for soprano and tenor soloists with mixed choir and may be performed with an orchestra, chamber ensemble or organ.