Found this bit of information on their website if it helps.
A. Children have been put in order of performance and the rank gives their position. If the boy’s rank is between 1 and 289, they must have been given a place at a School higher on the preference form.
B. If the boy is ranked between 289 and 388 he will be on our waiting list.
C. If the boy is ranked between 389 and 900, then he has not reached a standard suitable for entry.
So my DS2 who got a rank of 314 (score 303) was declined a place at HGS but he will be placed in the waiting list (not sure of the timeline when he can be offered a place