I was on the thread, and member it pretty well.
It was a pretty standard 'school review' type thread, with people steps pointing out that they could not think of another school which split pupils into two groups, and assigned then to legally separate bodies (a college and a faculty) so they appeared as two schools with differing results in league tables.
Also a lot of discussion on the nature and quality of their advertising.
And their (probably) unique T&Cs in that if your DC was in a scholarship/bursary and they left before end y13, then the entire value of the award had to be remain. No MNetter could come up with any other school with such terms. Posters warned people to be very careful, because even the most wonderful school can be a poor fit for an individual DC and when it's boarding you need to be able to move them asap (much more important than for a day school)
There were interesting posts on the complicated ownership of the school (well, it seemedcomplicated to me!)
Allegations from someone who purported to be from a former staff member were deleted, but IIRC were getting in to the territory f the events that have now been tested in court and resulted in convictions.
There was a link to a piece in the Telegraph (2015) about the extraordinary number of surveillance cameras on the premises
Somewhat unusually, posters responded to pleas to not speculate on the thread, or to rise to strange posts on it (fair few new posters, who then never posted on another thread) so that it did not end up so full of holes that it had to be taken down - determinined provocation of that type had caused a couple of others to go.
Now, with the benefit of hindsight, I think there are explanations for the school's litigious approach that go beyond what was assumed at the time (which centred on the odd split in reporting results, and the unusual amount of PR - possibly to attract international students, hence need to expunge readily discoverable stuff online that showed the holes in the 'top school' narrative.
Unfortunately it seems as if the concerns they did not want coming to light were considerably graver