There is something I should clarify about this story. Until 1961, when the Union of South Africa became the Republic of South Africa, the country was still a member of the British Commonwealth.
The example below is a typical Act of Apartheid. It ran to 50 pages. [http://disa.ukzn.ac.za/sites/default/files/pdf_files/leg19550706.028.020.069.pdf]
It was the Nationalist Party of South Africa that was responsible for the enactment of the Acts of Apartheid when they gained power in 1948. However, these laws bear the stamp of approval by the ruling monarch of Great Britain. The British in Africa, in India, and elsewhere, were notoriously racist. The Immorality Act, for example, was passed into law in 1926.
The present Queen Elizabeth was crowned in 1953, after the death of her father, King George VI. It is she who is referred to in the heading of the ACT.