While living in Preston as a young man, Watt was a member of the Reverend James Fielding's congregation.

Watt won the right to be the first official British Latter-day Saint convert by winning a footrace against eight others from Fielding's congregation that desired to join the Mormons.

In late 1850, the Watts returned to America and joined the new gathering of Latter-day Saints in the Salt Lake Valley in Utah Territory.

In Utah, Watt worked as a reporter for the Deseret News and as a private clerk for Brigham Young.

In 1852, Watt was appointed by Young to a committee that was charged with creating a new phonetic alphabet that would assist non-English speaking Latter-day Saint immigrants learn English.

Watt's obituary describes him as "honest truthful and sincere although perhaps misguided being a self-made man of strong character and exercising vast influence there is not a little in his career which is remarkable.