I think it's a pretty stupid measure, too.
I did 11 O Levels (all at grades A or B which was considered pretty good at the time) and would not have passed this test. None were in a humanity as, frankly, I was not very good at those subjects and not at all interested in them and it would have benefited nobody had I been obliged to do one of them. I'd have been bored, I may have got a worse result (how would a C in history have been an enhancement to my life instead of an A in German?) and they would have been entirely pointless in my later working/personal life. I think I am not entirely ignorant of basic historical and geographical facts now, being a reasonably bright person who has picked stuff up along the way and, crucially, followed a well-rounded curriculum before I had to choose. I have had plenty of opportunity to pick up the essay-writing skills and critical appraisal elements of those subjects in other areas. It was far better for me to be able to do a second modern language and a third science option as well as being able to take art which was a welcome relief from the other academic options.
Equally, there may be children who are far better served (in terms of what they are interested in and good at) by doing two or more humanities instead of a modern language or a science option. And why should RE, Economics or Politics not be included as humanities? It seems to me that they teach similar skills to Geography and History.
I went to a highly academic school which required, as well as Maths plus English Lang and Lit, Physics, Chemistry, Latin and French. A good proportion of my year would have also taken French AO or Maths AO or both, having done their O Level(s) early. A high proportion of my academic cohort would not have opted for a humanity, preferring music, art, a third language or biology. I don't think any of those are soft options and I reckon a good half of my year would have failed to gain 5 A-Cs in the five required areas. This is a school where about 50% of the intake went to Oxbridge. There is no way those students were being failed by their options. So it's a very blunt tool and doesn't really give a sensible picture, even if all IGCSEs were accredited. Where Hampton School is concerned, I'm guessing that the 6% who are the happy possessors of an English Baccalaureate are the very bottom of all their classes and have therefore been entered for the GCSE instead of an unaccredited IGCSE. This may be right or wrong in terms of difficulty, but it would be v interesting to know.
Also, I would be very happy with a school in which children were encouraged towards 'traditional' subjects but I honestly can't see the value in being so prescriptive about what they must be. Five out of English, Maths, sciences, music, languages, humanities and art/history of art would seem a much more sensible way to measure things. Maybe with English Language and Maths being compulsory - you do really need those.
I'm quite delighted OTOH that no notice was given as it will be v v interesting to see what happens in the next few years with children's potential choices at GCSE.