From February 1892 until 1902, Denham served as a member, and for four years as chairman, of the Stephens Divisional Board (later the
Shire of Stephens) based in
Annerley. He was a member of the
Legislative Assembly of Queensland from 1902 until 1915 representing the seat of
Oxley, and was
Premier of Queensland from 7 February 1911 to 1 June 1915. In June 1902 he was elected to the
Legislative Assembly of Queensland for
Oxley. He campaigned in opposition to a state income tax which
Robert Philp's government had proposed, although by the time he became premier in 1911, he had concluded that it was not high enough. In September 1903 Philp's government resigned when its income tax measures were narrowly passed with three supporters, including Denham, crossing the floor. A Liberal-Labour coalition government headed by
Arthur Morgan was formed and Denham was appointed Home Secretary and Secretary for Agriculture portfolios in the new administration. In April 1904, Denham became Secretary for Agriculture and Public Works, and in 1906 took on Agriculture and Railways as part of
William Kidston's government. In February 1907, sensing that a new anti-
Labour coalition could be formed, he resigned his portfolios. Ultimately, Kidston resigned as Premier in November 1907 following the Governor's refusal to appoint sympathetic members to the
Queensland Legislative Council, and Philp formed a new conservative ministry in November. Denham, now Home Secretary, became the Deputy Premier. However, the Ministry did not command the support of a majority of Parliament, and failed almost immediately, with a new election in
February 1908 returning government to
Kidston's party. However, later that year, Kidston amalgamated his own party with Philp's as the
Liberals, and Denham returned to the ministry as Secretary for Public Lands. On 7 February 1911 he succeeded Kidston as Premier. Denham's major contribution was the
Land Act 1910, which consolidated 50 years of Acts and amendments as well as historic New South Wales legislation still in force in Queensland, and removed much confusion. He was widely praised for his grasp of the legislation. While Denham commanded an easy majority in the Legislative Assembly, he did not always lead a united party – a parliamentary group known as the Farmers' Union emerged within the party in reaction to various legislation, while the Legislative Council refused to pass key legislation such as a 1911 liquor bill.
A tramway and general strike erupted in Brisbane on 18 January 1912, and Denham enlisted the police and special constables to deal with the strikers, who were criticised for their violent handling of the dispute. When the Commonwealth refused his request to send in the armed forces, Denham contemplated landing troops from a German warship to assist. He called an election, in which his government lost seats in Brisbane (mostly to Labor) but won new seats in rural areas and retained office. The Industrial Peace Act 1912 established an Industrial Court which did not recognise trade unions. The
1915 election saw the Liberal government swept out of power; 21 seats changed hands, with the main beneficiaries being the new Farmers' Union, an early precursor to the
Country Party, and the
Labor Party, which formed a majority government for the first time under
T. J. Ryan. Denham lost his own seat in the election, as did several of his ministers. Denham was the first of only two Queensland Premiers to lose his seat in a general election, the other being
Campbell Newman in the
2015 election. ==Later life==