The problem at Singapore was far worse than simpley a lack of British armor. For reasons that I have never seen properly explained the 2 pdr anti-tank guns were almost totally ineffective against the Japanese tanks. There is no design reason for this failure since the gun was effective against German and Italian tanks with similar armor. It is like the Singapore Garrison was shipped a batch of factory seconds in their ammo.
Could that be the correct answer? That the rounds shipped to Singapore were of lesser quality than those used in North Africa and Europe because someone did not take the threat of Japanese armour seriously enough. Could that ammunition have come from manufacturers who were inexperienced in producing 2bler AT ammo?