Which statute of the British Parliament fixed 15 August as the appointed day for setting up the Dominions of India and Pakistan?

Section 1 of the Indian Independence Act, 1947, passed by the British Parliament and assented to on 18 July 1947, provided that from 15 August 1947 two independent Dominions, India and Pakistan, would be set up. The Government of India Act, 1935 continued, as adapted, as the working constitution of each Dominion until its own Constitution was made.