In 1927 Armstrong made his first broadcast, in an organ recital for the BBC, playing music ranging from Buxtehude to Stanford and Parry; his long association with the BBC included many talks on the radio about topics such as British music. In 1928 he completed the three compositions required for the award of a Dmus: "A Passer-By" (a rhapsody for baritone, chorus and orchestra), a "Fantasy Quintet" for pianoforte and strings, and "Friends Departed" (for soprano, chorus and orchestra). From 1928 to 1933 he was organist of Exeter Cathedral, a post he held in tandem with the directorship of music at the University College of the South West.