The by-election was triggered off after C.V. Devan Nair resigned as MP for Anson to take office as President.

The PAP is returned for the seventh time, winning 77 out of 79 seats in the General Election. But its share of votes falls to 62.94 percent, a drop of 12.61 percent from the previous polls.

The opposition wins two seats: J.B. Jeyaretnam of the Workers’ Party is re-elected in Anson and Chiam See Tong takes Potong Pasir for the Singapore Democratic Party, defeating PAP's Mah Bow Tan.

The concept of Group Representation Constituencies (GRCs) comes into law, allowing for the election of MPs on a group basis to ensure the representation in Parliament of members from the Malay, Indian and other minority communities.

Parties contesting certain constituencies would have to offer a slate of three candidates, one of whom must come from a minority community.

The PAP wins 80 seats or 61.80 percent of the vote in the General Election. SDP’s Chiam See Tong is returned in Potong Pasir.

The battle for Eunos GRC stands out, with the WP team of Lee Siew Choh, Francis Seow and Mohd Khalit Baboo giving the PAP's team led by Tay Eng Soon a stiff fight.