@CutFlowers
You have raised something that is for me a fascinating and curious aspect of a longstanding (one-sided) debate, so brace yourself for a long-winded answer.
I am not a psychologist, but a lot of what is known about judgement stems from early medical research into diagnostic error, which was one of my research interests. I may be preaching to the choir if so I apologise, but most judgements that people make are necessarily heuristic, rather than analytical. The more people think that they know about a subject the more likely that is - experts are more likely to make heuristic judgements than novices.
I haven't reviewed this systematically (and of course my own bias comes into this) but I am reasonably certain that the people who agree with me on this thread have approached it analytically. They have read the research, and made additional points. Almost without exception, people who disagree with me have approached it heuristically - if the absence of any evidence of analysis allows that conclusion to be drawn. This is exactly what one should expect, for reasons that are obvious once you think about it.
People have a right to feel well informed about this. There is a great deal written about private schools and Oxbridge, all pretty much saying the same thing, and who hasn't heard of Sebastian Flyte? Everyone is an expert. So when I say students from private schools get more firsts, it doesn't require analysis, the explanation springs to mind immediately. But I also said this is evidence of discrimination against them. At that point one of two things happens, the reader doubles down on the heuristic, or the analytical process is triggered.Your post is almost unique because you have (quite obviously) not responded heuristically and you disagree.
The purpose of the paper that you read was to explore the reasons for the poorer performance of ethnic minority and disabled students. This was confirmed and the last paragraph states that the university should target activities to addess it. What is not discussed is that far from having an insignificant effect, school type is equally important.
The percentages are provided as percentages in the university's archives.
There is nothing in the peer reviewed literature that refutes the findings of the study that we are talking about.
Within sector school differences (in terms of Oxbridge entry) are only significant for the state sector.
As I have said before, contextualisation is a different matter.
In 2019 the Cambridge researchers "demonstrated the absence of any persistent trends in gaps in attainment due to participation (POLAR4) or deprivation (IMD) markers and identified sustained gaps in attainment between ethnic and disability groups as the main focus of work to ensure successful outcomes for all students" The 2020 paper confirmed it. The issue of poverty, holiday jobs etc is intuitive, and it is very often cited by people who present themselves as well-informed as being a reason for differing degree outcomes, but like many things that they say it is, according to (appropriate) research, wrong.
There are six essentials to understanding this (as far as I can judge) in temporal order: Naylor and Smith 2005 "Schooling effects on subsequent university performance"; Parks "Academic Performance of Undergraduate Students at Cambridge by School/College Background"; Cambridge archives for exam results until 2017 after which I have FOI figures; the university's participation and access plan; the paper above; and figures for changes in POLAR4 quintile admissions from an FOI to which I have briefly alluded elsewhere.