He was then appointed to a fellowship at the Bala-Bangor Theological College, and became a professor on 28 July 1926, following the death of Thomas Rees.

He taught Christian doctrine and the philosophy of religion and was regarded as one of the most able theologians of his generation.

He contributed to its newspaper (Y Ddraig Goch) and stood unsuccessfully as a candidate in three general elections and a by-election in 1945.

He was vice-chairman from 1931 to 1935, and succeeded Saunders Lewis as chairman in 1939 (holding the position until August 1943).

In 1946, Daniel was appointed as an inspector of schools, with special responsibility for classics and religious education.