We had that in Physics at Manchester in the 2000s. 4 students. I'm guessing they got the idea from Oxbridge, but I don't think it's been a USP for a very long time.
When I was at Cambridge in the early noughties, supervisions for maths and computer science (and physics I believe but I didn't go to any of those) were 2 students in 4 1-hour sessions per week (1 per 24 hour lecture course). [Edit: hmm, actually maybe it was just 2 per week.] In maths, if there were an odd number of students then one would get 1 to 1 supervisions, but I'm sure that depends on the college. For computer science, I was put in a 3 person supervision when they had an odd number (and I wasn't happy about it at the time!)
I later did teaching at UCL and Imperial and the difference was huge. When they get to it, I would advise my children to go Oxford or Cambridge in a heartbeat. (For reference, my parents were too poor to even consider university.)
A large part of uni is about learning to learn on your own and learning in groups - if everything is spoonfed, it might not be the best training.
Tutorials in Oxford are impressive for me for many reasons: 1. Those teaching were generally of a higher level beyond Ph.D., post docs or professors, all paid, all assessed against an NPS from students, and the performance of the students in exams 2. Tutors are generally teaching more adjacent topics (creating connections), students are challenged to think beyond the assignments (which are generally tough), 3. Tutorials are calibrated and personalised to students and made sure all students are challenged at the right level, I had tutorials where I had to teach 1:2 because the students were excellent and needed a higher level of complexity.
and having 4 people is very different from 2