Scroobal,
After recently doing some further reading on these issues, I am now more convinced on balance that Lim Chin Siong was indeed a communist or at least under communist influence. I think there is even some credence that Zaid Zahari fell into this same group in particular after looking at the Plen's comments to Zaid on Zaid's criticisms of the Plen's decisions with regards PRS in the early 60s. Oh and I also came across an indirect reference to Wee Mon Cheng
Btw Chin Peng seems to confirm that the Puthucheary brothers were not communists afterall and neither was Tan Wah Piow, but he did say that Juliet Chin was a communist. Rajaratnam himself told Mel Chew in an interview that he was drawn to communism (you were right before) on an intellectual level while in London like many young bright intellectuals of that time but probably followed the expression "if you are not a communist at 20, you do not have a heart, but if you are still a communist at 40 than you do not have a brain" similar to actually card carrying communist and later anti communist Gerald De Cruz(saw some sweet old photos of his young daughter long before she rose to the bench
Cheers
Knowing your rather good aptitiude towards objective assessment and my interest in the subject, I decided to dig deeper. Lo and behold you were right.
Apparently before the PAP came to power, the Special Branch under the British raided a pineapple plantation in Kranji looking for the young son of a pineapple towkay who was believed to be involved on the dark side. He was not there but they had come across literature on communism in his room.
One of the officers, a Chinese noticed that the house zinc was partitioned lower than the expected roofline and checked. The space yielded a small room and a bed. Underneath the carpet, below the bed, a space holding a biscuit tin. The tin cointained cigarette paper/rice paper and all of them carried tiny handwritings. This was the manner which the communist communicated where the paper would be rolled up and then folded until it was very small in the hand and easy to conceal by the courier.
On examination by handwriting experts, all the messages had the same writer and guess who it was - Lim Chin Siong.
That Chinese officer went on to become Perm Sec before retiring. Apparently, when the British decamped and handed over Singapore, they took the liberty of taking some files including one with the surname Lim and another with the surname Lee.
The young son of the pineapple towkay was subsequently picked up, his father got mad with him, son agreed to turn over a new leaf and Special Branch sent him to England to study for his cooperation.