To re-implement the University application process would indeed be a huge amount of work.

However, the governing principal of Cambridge University, for example, is that all operations are done at a human scale, and I think when you factor in the large numbers of staff whose labour the Universities have access to, it becomes possible.

For a group of applicants for Computer Science at a Cambridge college, for example, you would have a Director of Studies and one or two other staff ranking around 20 applicants for half as many places. (The ratio of applicants to places is much higher prior to interview.) It is a tractable problem to solve, even if for other institutions the process is scaled by 2x/3x (4:1 / 6:1, up to Nottingham’s reputed 13:1) or maybe even more.

An idea we mooted over dinner last night was for these applicant rankings to be fed to UCAS — the University and Colleges Admissions Service — and for UCAS to combine these rankings with the applicant preferences to fill up each course from the top down. No need for grades, just use the desirability metric provided by the institutions.

Grades themselves are a strange beast. By their nature they are different to raw marks. A grade speaks to your ability as part of the entire cohort of examined pupils in that subject. Without the exam, taken nationally under examination conditions, it just doesn’t seem to make sense to refer to grades.

If we called them “exam grades” perhaps the folly of trying to assign them to pupils, who have not actually taken an exam, would be clearer.

(I speak with no real authority, but I am a high school teacher in England.)

What's more, the people involved in the application process know the reputation of schools as well, both in respect to what kind and how much bias they have in terms predicted grades and in terms of how much the school tends to 'teach the test' or otherwise be good at grooming their students to get good grades or perform well at the interview, so a student who does well in grades or interview from an underfunded state school is more likely to get an offer than a pupil with equivilent results from a high-performing public school

There's still a substantial bias in offers towards public schools, but a lot of that is because such schools are selective like the universities, actual student ability does still matter and better schools still improve student ability more, and there's a strong self-selection of candidates for top universities (a lot of people who might get accepted for oxbridge don't apply because they don't think they have a chance) as opposed to old-school elitism in the application process. (Not that all of the above factors are actually fair from a grand socioeconomic viewpoint, but they are reasonably fair in as much as the university judging the merits of the applicants it gets).

Doesn't Oxbridge interview a lot of people very year anyway - so they are already geared up to a process that appears to be pretty different, and more labour intensive, than other institutions?

Yes. Holding interviews at each of Oxford and Cambridge are approximately 2 weeks of full time work for tutors, with paid full-time assistance from some students, and with admin from other college and university staff.