It was past 9 p.m., Sunday, 16 March 1975. Raja, the first Singapore leader to visit China since Singapore's independence, was in a Chinese-made Red Flag limousine, curtains drawn, being whisked through the near-empty streets of Peking to an undisclosed place. He was not told where it was exactly, but what he knew was enough. He was on his way to meet the ailing Chinese premier Chou En-lai (Zhou Enlai) at a place that the Chinese had described as a hospital.

The late-night arrangement was not on the programme when he arrived in Peking with a four-man delegation three days earlier. In fact, he was told about it only that very evening over a dinner, after rounds of intensive talks with Chinese foreign minister Chiao Kuanhua (Qiao Guanhua). The top Chinese diplomat, who had led Peking's first delegation to the United Nations in 1971 as China's permanent representative to the UN, was known to be a close associate and confidant of Chou.

There were several unexpected turns during Raja's nine-day goodwill mission from 12 to 21 March, but none as momentous as his dialogue with Chou. It was a landmark event in the tumultuous – and currently stalled – state of Sino-Singapore relations. It would in fact end a decade of official sullen silence and open a new era in relations between the two countries.

This, however, did not come without drama and mystery. Indeed, Raja's political reconnaissance to China felt not dissimilar to an expedition to a destination that had yet to be discovered. Much of the country was still caught up in the tumult of the chaotic Cultural Revolution. As with most things in the closed, paranoid China of that revolutionary era, Chou's health and condition were shrouded in secrecy. Also under wraps were the name and location of the hospital where he was convalescing.

The only thing that the Chinese hosts would divulge to the Singapore delegation, and indeed the outside world, was that the 77-year-old premier had been admitted since last May on his doctors’ advice for working without rest throughout the Cultural Revolution, which had begun in 1966. According to the official account, the hardworking Chou was often so busy that he could not meet his foreign guests until nightfall.

If Raja's pen was his sword, his office was his war room. It was where he analysed data, developed strategies and held court with visitors. On his wooden desk was a battery of books, journals, files, papers, notepads, and drafts of several works-in-progress: speeches, essays, messages. Taking entrenched positions were a rotary dial telephone, a shortwave transistor radio tuned to the BBC World Service, an adjustable desk lamp, an ashtray and a pack of cigarettes. The big gun sat in the centre, an Olivetti manual typewriter with its rapid-fire rat-a-tat. Alongside was his sword of choice, a blue-ink Sheaffer fountain pen.

Behind the arsenal lurked something surprising: an ingenious clock that ran on air. This was an Atmos clock, a device as close to a perpetual-motion machine as man could ever invent. It was a perpetual source of inspiration for Raja. It was powered by minute fluctuations in the temperature and air pressure of the surrounding environment. To convert a small amount of energy into motion, everything inside the clock had to work as smoothly and efficiently as possible.

The idea behind the innards of the Swiss-made clock, visible through the rectangular glass capsule, entranced him – that power could be generated from a high sensitivity to slight changes in the atmosphere. It required constant endeavour. It was an active force. The ability of the Atmos clock to accomplish much with very little in a small space had special resonance for the Singapore leader, who was constantly seeking to defy the limitations of running a small state.

The office attendant who cleaned Raja's office, Sanasi Ayakannu, was given strict instructions by Raja's personal assistant, Teo Ban Hock, that on no account were any papers on Raja's desk to be disturbed. This suited Sanasi, but the clock on Raja's desk puzzled him no end – it did not seem to have batteries, and yet needed no winding.

One day, Sanasi, who joined MFA in 1966, plucked up the courage to ask the minister: “Sir, where do you put the batteries for this clock?” Raja stopped his work, smiled, and explained the science behind it. Sanasi had his eureka moment, uttering: “It runs on air!” He became very fond of his minister, whose kindly manner despite the pressures of office contrasted with others who were gruff with him.

When I approached the trustees of S. Rajaratnam's estate in 2004 suggesting an authorised biography of the founding leader, I did not realise that the project would take over my life. Altogether, I have spent close to two decades conducting research for this two-part biography, trying to understand Raja the thinker, the writer, the politician, and the man.

I had known Raja since my days as a journalist, and had interviewed him in the 1980s and 1990s, both at his home and in his office. Writing his biography was the furthest thing from my mind then, but those encounters gave me a sense of the kind of man he was – his thinking, his values, his mannerisms.

By the time I officially started on his biography in January 2005, Raja was already suffering from dementia. With the permission of his trustees, I began to browse his personal library and private papers in his old bungalow in Chancery Lane, a process that continued until some months after his death in February 2006. Other than his vast collection of books, there were boxes upon boxes of unsorted personal papers, files, notebooks and photographs, all gathering dust. From among them I found useful nuggets of information, hitherto never revealed, that I have woven into the narrative of this book.

One of them was a letter that Raja had written from his hospital bed in London to his wife, Piroska Feher, in 1983. I learnt much more about their married life from this single letter than all the other sources and interviews put together.

Yet the more I researched, the more I also found that Raja's life was full of carefully guarded secrets. He was a discreet man, a private man. He did not keep a personal diary with intimate details of his life and career, although he kept copious notebooks on ideas or quotes he picked up from books and journals, and his thoughts on them.

He was firm about his decision not to write his memoirs. He gave many interviews and made many speeches, but, as a public figure with a deep abiding sense of privacy, he rarely revealed his personal feelings unless probed, and even then, he exhibited his reserve.

Raja was launching Singapore's charm offensive in Africa with virtually no diplomatic ties or trade links with any of the countries. From the moment he stepped onto African soil on 28 September 1965, he knew it would take all the collective strength of the team to pull it off. Not for one second did the foreign minister think that their island – a mere dwarf in international affairs – could command the attention of the African giants without extraordinary effort. Nothing would be handed to Singapore on a platter.

In pursuing his foreign policy goals, Raja found Toh a resolute partner, willing to go well above and beyond. By protocol, the DPM was the official leader of the Singapore delegation. In reality, however, “it was not really Toh's show”, as Herman Hochstadt, the secretary of the mission, said. “It was very much Raja’s. It was about diplomacy.”

Raja had a clear vision for what they needed to achieve: to build Singapore's image and reputation as an Afro-Asian partner. He considered it vital for Singapore to be accepted into the Afro-Asian bloc and represented in the forthcoming Afro-Asian conference at Algiers. It was a kind of preventive security policy, placing the small state in a multifaceted relationship with large and potentially aggressive members. There was reason to believe that Communist China and Indonesia – both non-UN members at the time – wanted to turn the Afro-Asian conference into a permanent assembly of the Third World nations, one that could exist independently from the UN. Singapore could not afford to be isolated.

Yet lurking at the back of his mind was the failure of Malaysia, cast by Indonesia as a British neo-colonialist plot, to obtain invitations to the October 1964 Cairo summit conference of Non-Aligned countries as well as the abortive June 1965 Algiers Afro-Asian summit conference – despite its lobbying efforts.

The Singapore mission's basic challenge was clear: to explain the anomaly of having a foreign base on the island and the apparent contradiction between Singapore's earlier advocacy of merger with Malaysia with its acceptance of Separation. While the African leaders might have regard for Lee, few would have forgotten the arguments for Malaysia that he had made so fervently before them in early 1964 during his African tour.

On 14 October 1979, Vietnamese-led forces in Kampuchea fired two 82 mm mortar rounds into Thai territory near its border. One hit a crowded refugee camp, killing and wounding many. It was the latest in a series of provocative actions by the Vietnamese as they shelled Khmer Rouge strongholds and refugee enclaves along the Thai-Kampuchea border. The escalating border clashes raised tensions to the highest since Vietnam invaded Kampuchea in late 1978, and stoked Thai fears that the Vietnamese troops would cross into Thailand.

Raja was seized by the urgency for ASEAN to get a grip of the volatile situation. He worried that the border clashes could draw Thailand into the conflict through accident or miscalculation, and this in turn could bring in China. He wrote to Malaysian foreign minister Ahmad Rithauddeen, who was then chairman of the ASEAN standing committee, suggesting an early ASEAN meeting “to discuss the border situation and collectively to be seen as giving moral support to Thailand”.

In his letter dated 26 October 1979, Raja said international reactions to the Thai-Kampuchea border situation would depend very much on ASEAN's lead. Rithauddeen, however, did not think a meeting was necessary. In his reply dated 9 November, the Malaysian minister said a meeting might give the wrong impression of an imminent invasion or attack on Thailand by Vietnam and cause “undue panic”.

This exchange showed how it had become second nature for Raja to think in terms of ASEAN when faced with a regional development – his instinct was to get the group together and to present a united position. But it also exposed the political reality: he had to work within the comfort level of his ASEAN counterparts.

These duelling factors came into play in one of his most ambitious initiatives: for ASEAN to co-sponsor a United Nations resolution to call for an immediate ceasefire and the withdrawal of Vietnamese troops from Kampuchea. In his thinking, such a withdrawal would help defuse the situation on the Thai border in the short term, and promote some sort of political settlement in the long term. He envisaged this as a prelude to the process of determining, by free elections, which leaders really represented Kampuchea.

With characteristic brio, Raja brought his global mindset to the deliberations in ASEAN. Sometimes his calls came off as the signature of a far-sighted strategist. Other times, of a brash maverick.

One such occasion was the ASEAN foreign ministers’ meeting in Pattaya on 16 April 1973, which was marked by an underlying sense of drift. In his speech, Raja sought to spark a rethink on ASEAN's growth strategy: besides expanding intra-ASEAN trade, the grouping should also seek to attract investments from developed countries. For this, they had to change the prevailing image of ASEAN from one of “political instability, contending nations and endemic violence” to one of “great growth potential”. This required countries to “mute, and if possible, remove causes for such conflicts”, he argued, and to focus on economic development and solving domestic problems.

His presentation at the opening session made an impression on the audience, at least according to British diplomat Arthur de la Mare. Raja's was “by far the best speech” of the day, he reported to London. “Rajaratnam was as usual listened to with great attention and respect,” observed the former British high commissioner in Singapore, who had been based in Bangkok since 1970.

In his despatch, the envoy contrasted Raja's speech with those of the other ministers, describing each in turn as predictable, platitudinous and pedantic, and in one case, likened it to comparing “Hyperion to a satyr”, quoting from Shakespeare's Hamlet. But what the classics scholar-diplomat did not see was the drubbing that Raja received from his counterparts in the closed-door session.

According to George Bogaars, then the MFA's permanent secretary, Raja had rather upset some of them by emphasising that ASEAN countries should focus on their economic development, encourage investment, bring about greater social justice and eliminate corruption. This, apparently, provoked “an emotional response” from the Filipinos, who accused Singapore of “turning its back on ASEAN” and of being more interested in Western Europe and North America than its neighbours.

Foreign interference is often about the long game. It takes time to stoke public anger against specific “unfriendly” policies, or against the government as a whole to the point when it could lose an election. It takes time to create the preconditions to destabilise a society and to erode the people's will to resist external intervention.

Raja and his colleagues therefore believed that in the case of individuals, groups or newspapers potentially serving foreign interests, if they were not stopped in their incipient phases today, they could mature to the point where they could cause Singapore serious harm tomorrow.

The move on 15 May 1971 to expose the “black operation” funding of the English-language newspaper Eastern Sun was calculated to signal clearly that no one, whatever his social, professional or political status, should believe that the patronage of outside powers would give him protection or immunity.

A government statement set out how the wealthy businessman Aw Kow, the son of one of the Tiger Balm brothers, had launched the paper in 1966 with financing from Chinese Communist agents based in Hong Kong. Their agreement was that the newspaper's policy would be dictated by Communist intelligence officials, and a Chinese operator would be appointed under their control to act as advisor to the Eastern Sun as a cover for his intelligence work. As part of the plan, the Eastern Sun would pursue a moderate editorial policy to gain respectability.

Aw Kow did not deny the charges. In disgust, the senior expatriate staff of the Eastern Sun resigned en masse. Soon after, the paper folded with little fanfare. The other two newspapers, Nanyang Siang Pau and the Singapore Herald, however, put up a vigorous fight. They denied the charges and sought to rally public opinion to their aid, both at home and abroad.

Fully aware of the scepticism among some over the “black operations” charges, Raja set out to educate the public. On the same evening of 15 May, he used the unlikely occasion of a reunion dinner of the Christian Brothers’ Old Boys Association to mount a lecture that stands today as one of the most concise and complete expositions of Singapore's policy towards covert foreign interference.

Completely pro-capital, pro-imperialist, anti-worker, antipeople” – these were some of the slogans brandished by the Barisan Sosialis and pro-communist unions against what they called the “blood-sucking, man-eating Employment Bill”.

Out to fan public alarm about the bill, they painted such slogans in public spaces, held protests, and distributed pamphlets saying that the proposed law “exposes the out-and-out vile, reactionary anti-worker, fascist features of the LKY puppets”. Their condemnations were soon joined by a chorus of anti-PAP critics lambasting the government for helping foreign investors and local capitalists to grow rich at the expense of the poor.

Raja had fully expected such vitriol from the pro-communists after he tabled the Employment Bill on 15 May 1968. He also knew that their defiance would put pressure on the NTUC, which was anxious to show that it was no PAP puppet. What he could not predict was how the general public would react.

The controversial bill had been crafted as an omnibus law to replace three former ordinances relating to employment and working conditions, but it was the 10 new clauses, of course, that provoked the outcry. Among other things, they limited sick leave, including hospitalisation, to 28 days (primarily to combat the malpractice of malingering); prohibited the employment of persons aged 55 or older, except by special permission of the Commissioner of Labour (aimed at freeing up jobs for young workers); and tied the payment of bonuses to productivity and performance rather than leaving it as a matter for negotiation (to maintain the incentive purpose of bonuses).

Another contentious clause involved payment for overtime work – it would do away with triple pay for work on public holidays and Sundays, and limit overtime work to 48 hours a month. This was to root out the practice of slowing down during weekdays in order to work overtime for the triple pay, and to encourage employers to hire more staff rather than make the existing employees work more overtime.

When S. Dhanabalan was posted to the foreign ministry as senior minister of state in February 1979, he swallowed his doubts and stepped up. Foreign affairs was, by his own admission, “not the kind of thing that intrinsically appealed to me”. His background was in banking and finance.

Dhana, as he was usually called by his colleagues, had started his career in the finance ministry. Armed with an honours degree in economics from the University of Malaya in Singapore, he had risen swiftly, helping to set up the Economic Development Board and the Development Bank of Singapore. He was the bank's executive vice-president when the PAP tapped him for politics at the age of 39 in 1976.

With his stellar record, he was one of the younger leaders groomed to form the nucleus of the next generation of Singapore's leadership. In appearance, he was clean-cut, urbane and short – about five feet tall – with an angular jaw and flashing dark eyes.

In 1978, when he was promoted to senior minister of state in the national development ministry, the work was well within his comfort zone. Not so his switch to MFA just six months later. Everyone was watching the 42-year-old political neophyte – could he make it as the potential successor to Raja, a political grandee at 64?

The reality was, for anyone – whoever it was – taking over from the founding minister, it would be like stepping into the shoes of a great, almost mythical, giant. Raja more than embodied MFA – he was MFA. He was its moving spirit. He had created it from nothing and given it life.

The foreign ministry's framework, strategies and priorities were all stored in Raja's mind, and even then, he was improvising as he went along. By 1979 when Dhana arrived, Raja had virtually become the sole authority in the ministry on external developments and foreign policy. Since 1965, every Cabinet portfolio except his as foreign minister had seen changes.

It was a measure of Dhana's stoic sense of duty that, when presented with the unnerving challenge, his response was: “Someone had to do it. I was prepared to take a shot at it.” It would be a baptism of fire.

Camera lights flashed as Raja strode into Paya Lebar airport on 16 September 1965. He was about to embark on his historic mission to the United Nations in New York as Singapore's founding foreign minister. For the first time since assuming the post, he looked the part. He cut a distinguished figure in a dark tailored suit, a crisp white shirt and well-knotted tie, accented by a pressed white handkerchief in his suit breast pocket.

A throng of supporters lined up to greet him with cheers, flower garlands and banners wishing him “Godspeed” and “Bon Voyage”. Flashing a beaming smile, he stopped to shake their hands. Aware of the public hopes pinned on his mission, he radiated a confidence that suggested all would be well despite the troubles of the moment.

He told the press: “This is the first effort by the Singapore government as an independent and sovereign country to put itself on the map of the world.” Then, in a pointed message to countries that had yet to recognise Singapore, he outlined two guiding principles for the proper conduct of relations between countries: “Do not ask us to take your friends as our friends. Do not expect us to take your enemies as our enemies.” He stressed: “Once relations between two countries were established on this basis, there is a chance that we may strengthen our ties and improve relations.”

Despite his brave face, many fears followed him. He boarded the plane with the heavy knowledge that, to date, only about 40 countries had individually recognised the newly formed nation – barely a third of the UN membership. Meanwhile, Indonesia was persisting in its hostile campaign to isolate Singapore from the Afro-Asian countries, portraying it as an Anglo-American imperialist stooge. At one point in late August, the path for UN membership had appeared so fraught with risks for Singapore that Raja had to consider the prospect of dropping it.

In a sign of Singapore's continuing troubles, the Commonwealth had not admitted Singapore into its fold – at least not yet. Commonwealth membership carried some weight as a badge of international legitimacy and respectability, particularly in Africa. Raja formed a suspicion, which he shared with British diplomat J.V. Rob on 16 August, that “Indonesian intrigues might be delaying matters”.

Perched on the front bench in the Singapore Legislative Assembly, Raja fidgeted in his seat as the debate over Malaysia stretched deeper into the evening of 13 November 1964. He was shortly due to open a high-profile international festival along Orchard Road, yet leaving the chamber was increasingly not an option.

It was a rancorous debate, with one opposition MP after another accusing the prime minister of breaking his promise of delivering a more prosperous and happy future for Singapore as part of Malaysia. Barisan Sosialis MP Kow Kee Seng typified their assault: “Malaysia has come about and what happens to the people of Singapore?” Only “difficulties, misery and unemployment all round”.

Lee was constantly on his feet, stressing the need to confront the new realities and to make Malaysia work. At one point, after repeated attacks for giving too much power to KL, he brought home the reality of it all: “If perchance things do not go right, and they go wrong, and Singapore does go south, then I concede to them the possibility in that situation of Malaysia breaking off.”

Grave-faced, Raja looked on with folded arms. He had no illusions about the political hazards ahead. The pro-communist Barisan, which had won 33.2 per cent of the national vote in the last general election in 1963, wanted Malaysia to fail, and the PAP to fall.

Raja, a strategist behind the merger campaign now being maligned, had only contempt for the Barisan's antics, and was not above heckling from his seat. But at this debate, he was taken aback by the PM's concession of a “break-off” possibility. It was an idea that, to Raja, was beyond ludicrous: it was unthinkable.

As he sat grimly through the debate, he knew he could not make it to the international festival at the Thai Consulate on Orchard Road. So, as he would whenever circumstances demanded it, he pressed his long-suffering wife, Piroska, into service.

The only certainty in life is an unformed future to be shaped to our will.” Raja scrawled this thought down in his private notebook in 1992 as his restless mind traversed over Singapore's journey of trials and triumphs. Now, at 77, he found momentary stillness in the idea, not so much as a meditation of what was left of his own future, but as a guiding philosophy for future generations.

As that entry in his diary shows, at a time when he had earned every right to bask in the glory of his achievements, Raja's mind was still on the future of the country and its next generation. How to design a “future-oriented” education, he mused, “which can convince youth that the future is not hopeless and that a decent place can be found for them in a meritocratic world”? Then, “the future and its shaping become something worth living for”.

And the answer, he believed, lay in an education that strove to instil in the young the will and the faith that they could achieve “even greater things in the future”. This was, in essence, his dictum for a future-oriented education: “Creating a better future for ourselves is a more satisfying life than the mere contemplation of grandeurs from another time.”

Diary jottings like these show a creative mind at work, but also a stout heart in action. One cannot help but marvel at the constancy of his faith in the power of the human spirit and imagination to shape a desired future, holding through disasters and suffering, through meandering and mean times, and now, through the bleakest hours of the evening of his life.

His solitary musings betray none of uneasy foreboding as to his own fate with his failing faculties. Perhaps they were his way of holding on, by grasping for beliefs and ideals that had powered him through the darkest of times when the odds seemed impossibly stacked against him.

It was 5 August 1967. In the fading light of the day, Raja found himself a lonely voice in a room with leaders from more powerful countries in the region. They were Adam Malik of Indonesia, Narciso Ramos of the Philippines, Abdul Razak of Malaysia, and Thanat Khoman of Thailand. Since about 4 p.m., they had been discussing the formal basis for what would become known as the Association of Southeast Asian Nations (ASEAN).

Their surroundings were deceptively relaxed. The five ministers were ensconced in an airy bungalow at Bangsaen, a seaside resort about two hours’ drive from Bangkok. Within the walls of the meeting room, however, the mood was getting as dark as the dusk outside.

Aware of Singapore's puny size and pugnacious reputation, Raja preferred to let the others state their positions first. He recognised the Asian concern for ritual and face. After all, he was here to make friends, not only to protect Singapore's interests. But he could not gloss over Indonesia's reference to “foreign bases” in the preamble of the draft declaration. As currently phrased, it basically opposed the presence of foreign bases, and could be read as barring individual members from relying on external defence ties for their security.

When consultations began months before, he had already made clear that this reference to foreign bases was irrelevant to the basis for the grouping. Yet, here it was, still in the draft in Bangsaen.

Nevertheless, Raja was hopeful that others would speak up on it. After all, Thailand and the Philippines – both members of the anti communist Southeast Asia Treaty Organisation (SEATO) – hosted US military bases on their soil and relied on external guarantees to ensure their individual security. So did Malaysia which, like Singapore, had British bases – both were part of the Anglo-Malaysian Defence Agreement that included the UK, Australia and New Zealand.

Furthermore, whatever their political and historical differences, all of them faced a common threat: Maoist China, which was stoking armed insurgencies and funding local communist movements in the region. The ideological divisions of the Cold War were being fought out at their very doorstep in the raging Vietnam War. Thailand, which played an important role in America's regional strategy, was at the forefront. This was obvious to everyone in the room – Bangsaen itself was heaving with American soldiers on rest and recuperation.

As a statesman, Raja had to work with the imperfect foreign regimes he faced, not with counterparts he might have ideally wished for. This could sometimes make for unpalatable diplomacy with dubious and even repugnant characters. This was the part of his job that he confessed he disliked most and found most trying. “As a foreign minister, I meet people. I form my own impressions. Some of them I find completely distasteful,” he said. “But I cannot afford to let them know about this.” In politics as in diplomacy, at times one had to engage in some dissimulation, he said, “which I find distasteful but which is necessary”.

Few encounters tested his ability to deal with the darker side of diplomacy than negotiating with the notorious henchmen of the Pol Pot regime: Khieu Samphan, Ieng Sary, and the latter's wife, Ieng Thirith, who was also Pol Pot's sister-in-law and the highest-ranking female in the regime. It was an unavoidable part of the tortuous business of forging a new coalition out of three incompatible Kampuchean resistance factions.

Besides the communist Khmer Rouge leaders, there were the two non-communist nationalist leaders: former head of state Prince Norodom Sihanouk, who was based in Pyongyang and Beijing, and former prime minister Son Sann, who was based in Paris. Compared with the Khmer Rouge, these two men were paragons of virtue. But they shared one major weakness as resistance fighters: they lacked the brute military strength of the Khmer Rouge, which was putting up the only credible resistance with its 35,000 troops well armed with Chinese weapons. On the other hand, the non-communist nationalists had a valuable asset that eluded the repulsive and reviled Khmer Rouge: respectability.

If the non-communist groups could join forces with the Khmer Rouge in a united front, they would recast the image of Democratic Kampuchea and sustain international support for the struggle. Together, they could exert greater pressure on Vietnam to accept a political solution and withdraw its forces from Kampuchea. And as part of a coalition representing Democratic Kampuchea at the UN, the two noncommunist nationalist factions could legitimately receive aid, including weapons, from governments sympathetic to their cause – just the way the Vietnamese were being armed by the Soviets, and the Khmer Rouge by the Chinese. That was the strategic logic that underpinned the coalition scheme conceived by Raja, its principal architect.