He was the youngest of eleven children born to Jane (née Douglas) and James Michie Watt, a farmer.

Watt was secretary of the North Melbourne Debating Club and served on the executive of the Australasian Federation League of Victoria.

He was prominent in the Australian Natives' Association and campaigned for federation, becoming a protégé of the Victorian liberal leader Alfred Deakin.

[2] In December 1913 the rural faction, now led by Donald McLeod, moved a successful no-confidence motion in Watt's government, with Labor support.

This forced the Liberal factions to re-unite, and a few days later Elmslie was duly voted out and Watt resumed office.

He was subsequently appointed Minister for Works and Railways in the second Hughes ministry and won re-election as a Nationalist Party at the 1917 election.

It was during his time as Treasurer that Watt opined that the war effort was best served by "...putting the country into the hands of a Committee of Public Safety.

He was a trusted figure in Melbourne business circles and shared the dissatisfaction that most conservatives felt at the increasingly erratic and autocratic way Hughes ran the government.

After the elections, the newly formed Country Party held the balance of power, and used it to force Hughes's resignation.

He was also chairman of trustees for the Melbourne Cricket Ground from 1924 to 1946 and the inaugural president of the Victorian division of the English-Speaking Union.