 In 1888, while still an apprentice, he was elected as a delegate to the Trades and Labour Council of Sydney and served on its executive and parliamentary committees through the 1890 maritime strike and the 1892 Broken Hill strike.In 1900, when the council reformed as the Sydney Labour Council, he was elected as its president and served until 1902, when the council decided to establish a paid secretary role and appointed Thrower to the position; in this capacity, he represented 77 unions and over 45,000 workers.As a unionist, he was an outspoken opponent of Chinese labour and business, especially in the cabinetmaking and grocery businesses.