Why did Junus Tan’s English sound so different from Singlish?

Some facts to set the scene:

1. Junus Tan was born to and raised by English-educated parents. Even his grandfather, Lee Hoon Leong, studied at Raffles Institution – then run and taught by teachers mainly from England.
2. Hoon Leong gave LKY an English name – Harry. (His siblings include Freddie, Dennis and Monica.) LKY didn't admire the British nearly as much, and gave none of his children English names.
3. LKY studied Law in Cambridge, where he no doubt spoke English to English folks, and came back to Singapore to practice law.
4. LKY's family presumably spoke English or Peranakan Malay at home – which is part of why he had to labour to get better at Mandarin in his later years.

LKY was raised and groomed to speak English – and not "Singapore English", but something more akin to "Queen's English". You can tell it from his vocabulary. He read old books quite prolifically and spoke with lawyers, judges and upper-crust people. He hung out with the Queen.

And it wasn't just LKY, really. If you listen to the other public figures at the time, everybody spoke English in a more crisp, pronounced way. JBJ comes to mind, but I'm sure you'd also hear it in the newscasters of the day. And if any of you have had the luxury of being taught English by an older teacher, you'd notice the difference, too.

I think the English language in Singapore since then has "diluted" a little – I don't mean that in a bad way, it's just a natural sort of stretching, ebbing and flowing that happens when more and more people begin to speak a language. The sharp bits get eroded away.