Our children attended local schools for two of the primary years and the education was simply excellent. They returned home with a good grounding in science and were at least 18 months ahead in math. The study discipline they picked up was great as well.
They are now attending one of the top private schools in Canada.
Keep in mind the following as well:
1) Raffles has been cited by the WSJ as the world's top prep school for Ivy League
2) Anglo-Chinese has absolutely dominated results from the the (highly creative) IB program
3) 1000s of Singaporean students attend Ivy and Oxbridge, and do very well
Some expats like to disparage local schools but they tend to disparage everything about Singapore. The education is very good by any standard.
what are this guy's chances of getting his kids off the boat and straight into one of these schools?
1 - Raffles takes the 'best of the best" from Singapore schools. (The WSJ rating was in 2004, by the way.) Yes, it has excellent results but it isn't representative of the general public school here. And, as stated, the population includes very few westerners. Trotting out Raffles and Hwa Chong (where Mandarin proficiency is mandatory) is useless as it is not relevant to the OP's question.
2 - Won't argue the basic point but your descriptor of IB as "highly creative" is arguable. It has become the standard in international schools so it hardly stands out anymore.
3 - Thousands attend? Hundreds, maybe. But just another exagerration.
If you plan to remain in Singapore for most of your child's K-12 education, you are committed to after school tuition every day, and you want him/her to learn Mandarin then consider a local school. Otherwise, there are dozens of international schools to choose from and most offer the (not highly creative) IB program. Some have IB in all grades though most only offer the IB diploma program the last two years of high school.