Howroyd was born in Dewsbury in Yorkshire, England and was educated at King Edward VI Grammar School in Wakefield and Turton College in York.

He was the secretary of the Federal Protection League from 1900, but was one of the founding members of the Tasmanian branch of the Labor Party when it was established in 1903.

[1][2][3][4] He was elected to the Tasmanian House of Assembly in 1906 for North Launceston, transferring to the new multi-member seat of Bass in 1909,[5] and topping the poll there in his re-election in 1912.

He successfully introduced or was heavily involved in the passage of legislation to introduce workers' compensation legislation in Tasmania, restrict shop opening hours, establish an eight-hour day for train drivers, protect deserted wives and establish hydroelectric works in the state.

He also served as a parliamentary member of the state executive and as president of the Launceston Workers' Political League.