First of all, let me say that I'm posting in my capacity as a mumsnetter, not as a representative of Cambridge law. Second, all undergraduate law admissions decisions are the responsibility of the Cambridge Colleges.
I don't know the precise statistics in answer to your question. But here's some information you might find useful (from this webpage : https://www.undergraduate.study.cam.ac.uk/courses/law-ba-hons Click on the tab for "Entry Requirements"):
"Most Law students (who had studied A levels and started at Cambridge in 2018, 2019 and 2023) achieved at least A-star, A-star, A (67% of entrants).
Most had usually studied at least one of:
- English (language or literature)
- History
- Languages (ancient or modern)
- Economics
- Law
- Mathematics
- Psychology
- A science subject
Other common subjects included:
- Classical Civilisation, Further Mathematics, Geography, Politics, Music, Philosophy, Religious Studies or Sociology.
The majority of students who studied IB achieved at least 43 points overall.
This information shows some of the common subjects our applicants have studied. Although these are common subject combinations, this doesn't mean they're favoured. "
I wasn't aware of the website in your post until you drew my attention to it. I think that it is trying to say that these are the "best combination of subjects to prepare for certain Cambridge university courses". Notice the sub heading: "Best subjects and combinations if you’re interested in arts, social science or humanities courses at Cambridge". It's not intended to mean these are the combinations that give you a better chance of admission. The idea behind the combinations is that the subjects listed are essay-based so they will teach essay-writing skills, which our students find very helpful. Personally I think a mix of academic essay-based subjects and science subjects is equally good preparation for law, sciences, and social sciences.
Unfortunately the University's website has been written in a clumsy way and it's meaning is ambiguous. I can see why you've interpreted it as a list of subject combinations that are weighted more favourably than all other A level subject combinations. But that's not the case. I'll raise the issue at work and ask for the website to be amended. Our websites should be expressing themselves as clearly as we expect our students to write!
The official advice for Cambridge law is here:
https://www.undergraduate.study.cam.ac.uk/courses/law-ba-hons
Note that there are zero subject pre-requisites from the Law Faculty: "We don't ask for any specific subjects to apply to Law."
In practice, I suspect some college Law Fellows may see certain A-level subjects as more academic, and therefore as slightly better indicators of potential for the Law Tripos. This could create a small unconscious preference for them over less academic subjects. The range of 'academic subjects' is very wide: English Literature, History, Maths, Further Maths, Geography, Philosophy, Religious Studies, Biology, Chemistry, Physics, languages, Psychology, Sociology, Music, Law, Politics, Ancient History, Classical Civilisation, Economics and many others. This is not an exhaustive list. Less academic subjects are things like Design and Technology, Art and Design, Photography, Performing Arts, Travel and Tourism, Physical Education.
There's a further sentence on the Faculty's webpage: "Check our guidance on choosing your high school subjects for advice about which subjects you might want to consider studying if you’re interested in applying for our arts and humanities courses." The word "might" is intended to say that the combinations on the other webpage are simply optional advice.
The Law Faculty also lists a few individual colleges that have published minor variations. For example:
-- Churchill college has a Law admissions website that states: "There are no subject requirements for this course. The following subjects are recommended: English (language or literature), History, Languages (ancient or modern)" https://www.chu.cam.ac.uk/undergraduate-courses/ideas-and-societal-systems/law/
-- St Johns college's Law admissions website :
"Essential subjects
None
Desirable subjects
There are no absolute requirements in terms of essential subjects or subject combinations for a successful application. However, it is advantageous for an applicant to be studying at least two of the following subjects, and to be predicted A* (or equivalent) in at least one of these: English Literature, History, Mathematics, Ancient History, Classical Civilisation, Economics, Further Mathematics, Geography, Philosophy, Religious Studies, sciences (Biology, Chemistry or Physics), or languages.
Students taking other possible subjects (including Archaeology, English Language, Environmental Science, Government and Politics, History of Art, Law, Music, Psychology or Sociology) should not be put off from applying; we have made offers to many students in the past who have applied with a subject from this list.
Please note that while Law A-level is a helpful social science, it is quite different from the Law course at Cambridge."
-- Lucy Cavendish's website states:
Required subjects: None
Useful subjects: At least one academic, essay-based subject, Mathematics* *
https://www.lucy.cam.ac.uk/subject/law
When it comes time to list apply to a Cambridge college, it would be sensible to check with your preferred college's admission office whether they weight any subject combinations favourably or unfavourably. If so, and your choices don't fit, you might want to apply to another college.