Image copyright Sonny Liew Image caption Artist Sonny Liew reimagines the history of Singapore in his graphic novel The Art of Charlie Chan Hock Chye

Modern Singapore: prosperous and peaceful, and led by charismatic working-class hero Lim Chin Siong. His political rival, Lee Kuan Yew, is living in exile and ignominy.

This scenario - ludicrous to Singaporeans celebrating 50 years of independence led by Lee - was dreamt up by local artist Sonny Liew in a new book which imagines an alternative history.

But in the years leading up to Singapore's independence there really was a bitter political battle between Lim's leftist Barisan Socialis party and Lee's People's Action Party (PAP), one that arguably defined the path of the nation.

Stifling dissent?

During the instability after World War Two, Singapore and the rest of British Malaya saw a violent anti-colonial and communist insurgency.

In a subsequent crackdown in 1963, Lim and other Barisan leaders were detained, accused of being part of a communist terror network out to overthrow the authorities.

A wave of arrests followed of people accused of communist subversion which continued until the late 1980s. At least 690 people were detained without trial while others fled.

The official narrative is that they all posed serious security threats and had to be neutralised for Singapore to become a stable capitalist democracy.

But to this day, some of those detained maintain their innocence, and in recent years more voices have emerged accusing the PAP of using this narrative as a smokescreen to stifle dissent.

Singapore communist crackdowns

1963 Operation Coldstore: More than 130 communists and leftists arrested, some held for years without trial

1963-1988: At least 690 people detained, with many accused of being "Euro-Communists".

1987 Operation Spectrum: Sixteen Catholic church workers and professionals accused of a "Marxist conspiracy" and held for nearly three years

Image copyright Sonny Liew Image caption In Mr Liew's alternative reality, Singapore prospers under Lim's rule while Lee is in exile

So was Barisan really part of a terror network?

The government certainly still says so. Just last year, it said the Barisan was "not an ordinary left-wing political party, and its leaders were not 'unwitting dupes' of the communists" but was planning "to use violent unconstitutional means to overthrow the government."

But former Barisan leader Dr Poh Soo Kai, among those arrested, insists this was not true.

"There may have been some communists in our party, but we were not following their orders. We did not want terrorism, we were committed to constitutional reform," the 83-year-old says.

Image caption Dr Poh was Barisan Sosialis' assistant secretary-general

Dr Poh was imprisoned twice, once in 1963 and again in 1976. He spent a total of 17 years in jail without trial.

He says the real reason for his second arrest on subversion charges was because of his civil rights activism and criticism of Lee Kuan Yew.

He now lives in Malaysia, returning often to Singapore in his campaign for alternative views of history to be recognised.

"I want to show that the government has not been telling the truth because they just want to be in power. Truth is on my side and I must explain this for future generations and for history," he says.

Image copyright Otto Fong Image caption The older Mr Fong, seen here with his son Otto, was a key union leader for bus workers

Another Barisan leader, Fong Swee Suan, was also imprisoned in 1963 and then lived in exile until the 1990s. He maintains he was never a communist, and also denies the charge that he instigated deadly riots among striking bus workers.

"I want people to be aware that my father has made a positive contribution to Singapore," says his son Otto Fong, speaking on his elderly father's behalf.

"He helped workers organise their unions. He only wanted to speak up for their needs, and make the relationship between employees and employers better."

With the government continuing to reject his father's claims of innocence, "there is a whole nation of people believing in something that is not healthy," he says.

Lingering doubts

Recently declassified British documents detailing discussions among the city's leaders have led some to see the Barisan arrests as a politically expedient decision.

Historian Thum Ping Tjin argues that Singapore's leaders viewed Barisan as an electoral threat, while Britain believed the party would be uncooperative if it won power.

"The fact that [the Singapore authorities] have not released any evidence which contradicts my work suggests that they have none," Mr Thum says.

Image copyright Sonny Liew Image caption Another controversial crackdown depicted in Mr Liew's book was the 1987 "Marxist Conspiracy"

There have also been doubts about subsequent crackdowns - one cabinet minister resigned over arrests made in 1987.

Lawyer Teo Soh Lung, who was detained at that time, says: "We were not politicians. In today's context you would consider us social activists. We were conducting open and legitimate activities."

Image caption Ms Teo is now part of an activist group that is campaigning for the abolition of laws that detained her and others without trial

Legacy of intolerance?

The arrests set Singapore on the path to the PAP-dominated capitalist state it is today, with no powerful opposition.

Singapore historian Kumar Ramakrishna believes the 1963 crackdown was "important to remove the communist threat".

Had the threat not been quelled, he says, communists "would have more deeply penetrated our body politic and destabilised not just Singapore but also relations with Malaya".

Image copyright Tan Pin Pin Image caption Documentarian Tan Pin Pin's film on political exiles has been banned from being shown publically in Singapore

But critics point to a chilling effect on society.

Singaporeans "tend to react badly when people present a different point of view, because clamping down is the only way we know how to deal with dissent," says Otto Fong.

Read more: Amos Yee, the boy who insulted Lee

Yet as Singapore turns 50, the struggle to control the narrative of the past continues.

Some of the ageing detainees have published their accounts and younger Singaporeans have made films or written books about the crackdowns.

But censors banned public screenings of a film on political exiles, and a national arts fund pulled its grant for Mr Liew's graphic novel. The works were deemed to have "undermined government authority".

The government has also reprinted a book promoting its version of events, and published strenuous rebuttals in local media.

Image copyright Sonny Liew Image caption In Mr Liew's book, the alternative reality of Singapore led by Lim Chin Siong is torn apart

As for Mr Liew's alternative vision of Singapore, it does not prevail. At the end of his book a ghostly apparition with Lee Kuan Yew's face turns back time, insisting there was only one path that Singapore could ever have taken.

While it might be futile to re-imagine history, says Mr Liew, "that does not mean that there is no point to exploring alternative interpretations".

"It is only when we allow for a greater variety of voices that we can come to a better, richer, understanding of our past."