The UK newspaper The Guardian has published its UK university league tables - I would advise everyone considering using this table for their LLM to read the comments about their methodology:
http://www.guardian.co.uk/education/2010/jun/08/oxford-top-university-league-table#start-of-comments
If you are considering using undergraduate tables for your LLM application, I would ask you if you consider gossip about local doctors/general practitioners as a guide for a specialist neuro-surgeon?
No? Thought not.

Why only put the warning notice on the Guardian rankings?

All the rankings focus heavily on undergraduate experience.

The most useful table for LLM students is probably this one:
http://www.guardian.co.uk/education/table/2010/feb/15/law-postgraduate-masters-table1

True.. Rankings r not to b relied upon.. Give them a glance n move on.. They will confuse you and you will wonder 'how come every year I see the same Universities appearing on top year after year, and such disparity in my University's ranking this year as compared to last year'... Think...

I am sure Kerfuffle reads beyond the headlines - and to reiterate their advice: do not trust any of these league tables. The only useful (and even so, perilous) measure of UK law schools' ability is the government's Research Excellence Framework: http://www.guardian.co.uk/education/table/2008/dec/18/rae-results-2008-law-degree
The reason its useful is because all law schools cooperate in its production and it is the basis for the allocation of research funding by government. It of course can't predict how much that brilliant research will contribute to your teaching experience, but as postgrads you should expect research-led teaching (which we can only dream about for undergrad lawyers).

Yes, Kefuffle does read beyond the headlines... (??)

I don't believe the RAE (now REF) is a very good benchmark for LLM students to follow - it's simply too generalised. Of course it's something to consider when weighing up a course, but I personally wouldn't place any more emphasis on it than any of the data.

Whether we like it or not though, students do take notice of rankings and so do many employers.