BaadBadBunny Unless you attended that open day before the equal Preference System was introduced, the Head was not presenting the picture accurately. It isn't a matter of 'some schools might do it differently' - the schools admissions code, including the 'equal preference system' is LAW.
Yes, the school will tell the LA who they can offer a place to, and who has passed at a high enough level to be in the reserve list. That is what happens: the school tells the LA who can be admitted under their published admissions criteria.
The LA looks at all the offers of this kind that a child has, and offers the school highest up the list. It would be perfectly possible for someone who had taken the exam for his GS, passed with top marks, to have, nevertheless put another school first. Say the other school was miles away, with a distance criteria, or had an even higher superselective pass mark, and the child was NOT offered a place at that school. The LA would then look at the next place on the list of preferences that was offering a place - 'your' GS. And so they would be admitted, having placed it second.
The way someone could mess up would be to put a non-GS which was on the doorstep first in the list - and then however high on the GS admissions list they were, they would not be offered the GS because they were offered a place at the school they put first.
So: a mistaken interpretation by that GS Head.
It helps spread myths, YEARS after the equal preference system was introduced.