No - it's based on the end-to-end length of the ticket coupons. But since I believe each of the four flights you mention is a separate coupon then you will get the miles and points you suggest.

(On the other hand,for example, LHR-SYD via SIN ticketed as one coupon earns miles for the end-to-end distance, not LHR-SIN + SIN-SYD)