[2] After his time in the Rifle Corps, Coles enrolled in the British Band of the Allied Expeditionary Forces (AEF), where he played trumpet and arranged for its conductor, George Melachrino.

[2] He went on to form, at the request of the BBC, a larger, 22-piece light orchestra named 'Jack Coles and his Orchestre Moderne' which lasted over a decade.

Throughout the 20th century, Coles composed and arranged light orchestral music for radio, television, film and stage productions.

He evolved a distinctly modern rhythmic style and composed both contemporary light music and popular standards of the time.

Coles' musicianship, program-building and conducting ability were held in high regard by the BBC and earned him a favorable reputation.