Browsing through Elections in Singapore written by Pugalenthi Sr and published in 1996, I was struck by this passage, where he writes about the 1959 elections, which brought Senior Minister Lee Kuan Yew to power:
He said the citizenship laws had deliberately been made very liberal to allow Commonwealth citizens to take up citizenship after a stay of only two years here. This was aimed at providing the large number of Britons here a say in local politics. But most of these Britons had no intention of making this their homeland and would "scoot off" as soon as things "got hot here".
The book does not give any references.
But Mr Lee and his People's Action Party in those days did strike a chill in the hearts of expatriates, according to the historian Constance Mary Turnbull. In A History of Modern Singapore (1819 – 2005), she describes the aftermath of the PAP victory in the 1959 elections, when PAP won 43 of the 51 seats (see the Elections Department page and Wikipedia: total voters 586,098, voter turnout 527,919 or 92.9%). Turnbull writes:
The PAP's clear victory at the polls struck chill in the hearts of most conservatives, businessmen and property owners, especially expatriates, who regarded the election as the prelude to irresponsible and vindictive government and ultimately to communism… The intensity of the PAP's election campaign and the party's record of extremism and inciting workers against employers frightened the professional and commercial community. European clubs prepared to be closed down, the price of property slumped, there was a flight of capital, the Straits Times and many foreign firms moved their headquarters to Kuala Lumpur, and a general air of gloom and foreboding in business circles augured badly for the future economic health of Singapore.
The immediate aftermath of the election increased these fears. Lee Kuan Yew refused to take office until PAP detainees were released, and he gave several of them posts in his government. The new regime launched an attack on Western culture and pressed heavily on the hitherto privileged English-educated middle class. Six thousand civil servants suffered a cut in allowances and were drafted into carrying out "voluntary" manual work on Sundays. Western films and magazines, which were held to have a corrupting influence or to belittle Asian culture, were banned. Liberal terms for British subjects to obtain citizenship were withdrawn.
In reality the situation was less unsettled than it appeared. Some of Singapore's most critical problems, such as education, language and citizenship, were already well on their way to solution… After the 1958 constitutional talks in London, Lee Kuan Yew had satisfied the Colonial Office that he could form a moderate government and contain the disruptive elements in his party. During the 1955 and 1959 Assembly elections and the municipal election campaign of 1957, the PAP moderates ranted against colonialism and promised socialism, but they preached social welfare, not ideological Marxism-Leninism. In 1959, while emphasizing self-reliance, they acknowledged that foreign capital was essential for building up the economy. They planned radical changes in Singapore, but, as Lee Kuan Yew promised in a broadcast speech at the time of assuming office, this was to be "a social revolution by peaceful means".
The need to retain the support of the Chinese-educated masses and to keep to the left of the Labour Front government had driven Lee Kuan Yew to cultivate an extremist public image that was at variance with his long-term political thinking.
An article in the Melbourne Age on July 8, 1960, one year after the PAP victory, said: "One of the criticisms of the present (Singapore) government is that it still employs too many British expatriates."
However, the Singapore Citizenship Ordinance of 1957 – which gave citizenship to all residents born in Singapore or the Federation of Malaya, British citizens who had been resident for two years, and others who had been resident for 10 years – was repealed after independence. Singaporeans had become Malaysian citizens following the merger with Malaysia in 1963. So, on independence, they became Singapore citizens again under the new Constitution.