@mumsneedwine - I was disagreeing with your statement that "Medicine is still v v heavily weighted with private students." Hence the quoted statistics. Anything over 14% (approx proportion of A-Level students who attend private schools) is too high, but there are many medical schools whose privately-educated intake is lower than this. I don't think it's fair to accuse us all of favouring applicants from private schools.
I agree with you that the criteria for WP and "contextual" status are sometimes perverse. Universities are judged on their commitment to widening participation but we have been asking for a definition of WP for at least 20 years and none has ever been forthcoming, so each university defines it in its own way. Many of these definitions are based on postcode data that are, at best, misleading and that the Office for Students itself says should not be used to define WP status.
Grammar schools are troublesome. They present a massive problem for places like Kent & Medway, which wants to recruit local, disadvantaged students but has to negotiate a local school system where 70% of students are excluded from academically oriented schools and many of these attend schools/colleges that don't offer A-Levels. As entry to grammar school is far too heavily dependent on parental input (coaching, buying private tutoring, etc.), this obviously has a disproportionate effect on less well-off, first-in-family in HE students. On the other hand, in many inner-city areas, grammar school students are predominantly the children of low-earning Asian & African parents and their teachers argue passionately that the students are significantly disadvantaged.
We all work in a very messy system. It is worth calling out universities on WP/contextual criteria that offer advantages to already-advantaged students. If enough people join in, they will change. It's usually inertia rather than intent that allows these anomalies to persist.