@Johnathonripples
It doesn't really work that way.
It used to...in the sense they used to look at the result last in isolation, now they look at them in context because it's deemed to be a better way to assess potential.
So by way of example a child at a top flight selective public school may have gained 12 x grade 9's. That's obviously a fantastic achievement. However in that school, it's not an unusual occurrence and other students will have attained the same results (or very close to it). Even "average" students in that school walk away with 10 GCSEs most of which are grade 7 and above perhaps with a smattering of 6's.
In comparison a child in a poorly performing non selective state school may have results of 1x grade 8, 2 x grade 7 and 6 x grades 5 to 6. However that's an outstanding result in that school and way above the average grades a pupil in that school would have been expected to achieve.
In context the achievements of the latter would be "ranked" just as, if not more highly as an indication of future potential.
These are obviously extreme examples but you get the idea.
Two children with the same grades would not necessarily rank the same when you put their results in the context of the overall results of the school they attended.
That said GCSE results are just one part of the admissions assessment. They are also looking at predicted A level grades and the personal statement.