 Thereafter, every seat in Parliament was held by a PAP MP until Joshua Benjamin Jeyaretnam of the Workers' Party of Singapore won a 1981 by-election in the Anson constituency.Jeyaretnam retained his seat at the following general election in 1984, at which Chiam See Tong of the Singapore Democratic Party was also elected as representative of Potong Pasir.Between 1984 and 2011, the number of elected parliamentary seats held by opposition parties fluctuated between one (after the 1988 election) and four (1991 election).