The figures for colleges can be all over the place because they have 16-19, adults, ESOL all sorts of students who may take A Levels.
I did an AS level a few years ago, I forgot to turn up for one exam <dumb blond emoticon> so my result was a D. If I'd been 17 and relying on it I wouldn't have forgotten.
So you are actually looking for their 16-18 data, and for the subjects your dd wants to do.
You also want to know how many students pass, not just the %, a friend's son is currently in a class of 3 for A Level maths so a % is not going to be an acccurate measure.
Also some colleges let students take AS and if the results are not good they steer the students to BTEC, which can be what is best for the student, but means the A Level results are skewed compared to somewhere that only offers A Levels.
League tables aren't the most important thing. Want you want to know are how well they do in the three or four subjects that DD will be studying. They could get 30 pupils a year to Oxbridge to read medicine but if DD wants, say, Humanities subjects then it is irrelevant to you.
Most places issue their own detailed results which show subject-by-subject, grade-by-grade how they did at A2. If they don't, then you have to wonder why not.
Also, be careful of boasts about UCAS points: they are sometimes inflated by Gen Studies, Critcal Thinking etc.
There was an article in The Independent a couple of weeks ago which listed the top 100 comprehensives (therefore I think non selective for 6th form) for A levels in the country. I'll see if I can find it.
Does anyone know if you can get league tables for colleges and sixth forms which show their exam performance for A level?
I can only find ones for GCSEs at secondary leve on the internet. DD is brandishing all kinds of prospectuses at me on the basis of them having Ipads and looking shiny as far as I can tell. She says she knows a particular college is good because her friend's cousin goes there and says it's great