Government of India Act 1919 in the context of "Diarchy"

The Montagu–Chelmsford Reforms or more concisely the Mont–Ford Reforms, were introduced by the colonial government to introduce self-governing institutions gradually in British India. The reforms take their name from Edwin Montagu, the Secretary of State for India from 1917 to 1922, and Lord Chelmsford, the Viceroy of India between 1916 and 1921. The reforms were outlined in the Montagu–Chelmsford Report, prepared in 1918, and formed the basis of the Government of India Act 1919. The constitutional reforms were considered by Indian nationalists not to go far enough though British conservatives were critical of them. The important features of this act were that:

1. The Imperial Legislative Council was now to consist of two houses: the Central Legislative Assembly and the Council of State.
2. The provinces were to follow the Dual Government System, or diarchy.

The present state of Tamil Nadu is a residuary part of the erstwhile Madras Presidency and was formerly known as Madras State. The first legislature of any sort for the Presidency was the Madras Legislative Council, which was set up as a non-representative advisory body in 1861. In 1919, direct elections were introduced with the introduction of diarchy under the Government of India Act 1919. Between 1920 and 1937, the Legislative Council was a unicameral legislature for the Madras Presidency. The Government of India Act 1935 abolished diarchy and created a bicameral legislature in the Madras Presidency. The Legislative Assembly became the Lower House of the Presidency.

After the Republic of India was established in 1950, the Madras Presidency became the Madras State, and the bicameral setup continued. The Madras State's assembly strength was 375, and the first assembly was constituted in 1952. The current state was formed in 1956 after the reorganisation of states, and the strength of the assembly was reduced to 206. Its strength was increased to the present 234 in 1965. Madras State was renamed Tamil Nadu in 1969, and subsequently, the assembly came to be called the Tamil Nadu Legislative Assembly. The Legislative Council was abolished in 1986, making the legislature a unicameral body and the assembly its sole chamber.