18 May 1956
The Separate Representation of Voters Amendment Act No 30 of 1956 came into effect, amending the 1951 Separate Representation of Voters Act No 46 of 1951 to remove Coloureds from the common voters roll in the Cape. The Act No 46 of 1951 was declared invalid by the Supreme Court on constitutional grounds. The Senate was enlarged to obtain the required majority votes, which would ensure them a victory to re-enact the Act in 1956. The means used by the government to achieve its purpose were severely criticised by the opposition - even within the ranks of the National Party (NP) there were people who did not approve of the government's actions. Thirteen lecturers at the University of Pretoria, all NP supporters, signed a petition against the enlargement of the senate, but all protests were to no avail.
Sources:
http://www.sahistory.org.za
http://countrystudies.us/south-africa/25.htm
Muller, C.F.J. (ed)(1981). Five Hundred years: a history of South Africa; 3rd rev. ed., Pretoria: Academica, p. 480.