The first meeting of the "provisional" county council was held on 14 February 1889 at Westminster Town Hall.

Although the council did not use political labels, among the aldermen elected were members of the parliamentary Conservative Party.

From 1919, the scarcely political composition of the council was challenged by the election of members of the Labour Party.

[3] Labour continued to make advances at the 1931 election, and this led to the formation of a Middlesex Municipal Association "representative of all anti-Socialist members".

The chairman of the county council chaired its meetings and also represented it in a ceremonial manner, in a similar fashion to the mayor of a borough.