It was a mere two years after Singapore was granted self-governance by the British when the Anson by-election took place in 1961.

Prior to the by-election, the Criminal Investigation Department (CID) was told that an attempt would be made to kill then-Prime Minister Lee Kuan Yew and other ministers.

The plot, according to a Straits Times report, was allegedly hatched by secret society gangsters and was set to be executed at the PAP Anson by-election rally at Maxwell Road.

Investigations carried out

Following the tip-off, investigations were immediately carried out by the police and the Special Branch.

During that period, secret society members had gained notoriety as they were unafraid to resort to violence in order to achieve their objectives.

Besides, any information regarding an assassination attempt on top Singapore politicians was sure to be treated with grave importance.

To investigate this case, the police rounded up a number of suspects and interrogated them at the Special Branch's headquarters at Robinson Road.

Under the Criminal Law (Temporary Provisions) Ordinance, these suspected criminals could also be detained without trial.

Such powers were originally introduced in 1955 to combat fights and crimes committed by secret society members, but has been extended most recently in 2013.

Apart from detaining suspects, a series of raids was also conducted in many areas, such as Paya Lebar, Upper Serangoon and Geylang.

The raids culminated in the arrest of a big-time racketeer and 10 others.

Hand grenades were also seized by the Special Branch during a raid conducted in the racketeer's residence.

David Marshall's accusations

When news of the bomb scare broke, David Marshall, the Workers' Party candidate for the Anson by-election, said that he "found it difficult to believe that anybody in Singapore was mad enough to want to indulge in violence when there was available machinery for peaceful change".

Speaking at the by-election rally, he also suggested that the bomb scare was merely a cheap propaganda trick engineered by Lee to win sympathy.

These accusations, however, were unsubstantiated.

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Nothing more than a hoax

Several days later, the police released a statement concluding that the incident was nothing more than a hoax.

According to a statement by the Police Secretary, Lim Seng Huat, the false threat was in fact a conspiracy between a police informer and detective corporal for personal gain:

"It would appear that the informant and the CID detective embellished what may have been an attempt to create disorder at the rally into an assassination plot to ingratiate themselves with the police, the informer in the hope of a reward and the detective presumably hoping for a promotion."

Lee also brought up the incident in The Singapore Story, where he revealed that the hand grenades were planted:

"Interrogation revealed that an informer had fabricated the assassination plot and planted the hand grenades with the connivance of a Criminal Investigation Department detective corporal…Nevertheless, until the threat was found to be fiction, I was faced with the real problem of how to respond to it."

Both the police informer and detective corporal were arrested, and the corporal was suspended from duty.

Top photo adapted from NAS and Newspaper SG