I don't think the QS university rankings are considered relevant in the UK. They are very key for example for applicants from foreign countries seeking scholarships where there is a requirement for "top 100 worldwide" or whatever.UOB is ranked 11th or 12th in the UK. I don't think you can really say it's not one of the top universities. Also, a lot of the top 100 are US universities. I'm gonna go out on a limb to say most US students are not coming to the UK to apply to a US firm following their law degree, but rather applying in the US directly, therefore the World ranking doesn't seem as relevant as the UK one.
However, I would avoid citing them in the UK. They are deliberately gamed by universities seeking foreign students and do not necessarily use relevant measures.
In addition, while undergraduate university is a strong indication of academic ability, the fact is about half (?) of English corporate lawyers do their legal education at a degree mill (Ulaw, BPP), so the idea that corporate clients are concerned that you learned about Shakespeare (or whatever your undergraduate degree was in) from the best profs at the best uni is a little unlikely. Plus general rankings don't reflect individual subject expertise.