Willcox made his first recordings with the Collegians, and remained with Whiteman for three years, building a reputation as a good reader with a full, richly burnished tone which sat well with the leader's preference for a sweet, sophisticated ensemble sound, rather than the more earthy approach of the hot bands.
Shortly after, cornetist Bix Beiderbecke and saxophonist Frankie Trumbauer also joined the band, making it one of the stellar ensembles of the day.
In 1927, and with a family to raise, the trombonist opted for the greater certainties of joining his father's coal business rather than pursuing the life of a professional musician.
In 1975, Willcox was invited to take part in a reunion concert for the Goldkette band at Carnegie Hall, where he renewed acquaintance with violinist Joe Venuti.
Venuti persuaded the trombonist, now retired from the coal business, to join him on a series of club engagements, and they worked together until the violinist's death in 1978, by which time Willcox had firmly re-established himself on the music scene.