whose dc has got into Cambridge from state school?

Well, Cambridge doesn't offer finance or business until what's known as Part II of the Tripos degree (unless this has changed recently), but she could apply for Maths or Economics... And they'd love to see her too (if she's got the right results so far), as women are under-represented in these subjects.

I got into Oxford from a decent state school. Only one to apply in my year and only one to get in. I was totally unprepared for the interview, and to an extent I think it helps. Its easy to stand out as memorable against a bunch of prepared kids from Westminster. i got in, as did a friend who went to the local secondary modern. We both had a great time, and met lots of people there who weren't as bright as those we went to school with. People there aren't as bright as they're made out to be.

not my dc (far too young) but i work in a 'truly' comprehensive school up north and 3 or 4 of our sixth formers get into oxbridge each year (about 7 apply). She can but try.

I did - but it was eighteen years ago. Does she think she has no chance because she's at state school or because she doesn't think she's up to it academically? If she's been predicted 3 or 4 As at A2 and has a good range of co-curricular activities there's no reason why her application shouldn't be considered. They will be looking for things like music, drama, sport, DofE, young enterprise, peer mentoring, community service, hobbies/wider interests to support the academic qualifications. If she's taking any Advanced Extension Awards, that will look good too.

I was at Cambridge, and supervised and interviewed there, and while there are a higher proportion of students who attended independent schools than at other universities (though not all, incidentally: I think Bristol, or somewhere, has more), it is absolutely not the case that if your dd is bright enough she won't get in because she's from a state school. Most Cambridge colleges work really hard to overcome this perception of them (access officers, student ambassadors, etc) and are delighted to talk through issues, etc., with state school applicants. I could give you more advice, if you like.

about 50% of kids at Obbrige are from state schools IIRC.

Now, I realise that is an under representation, but it is still quite a lot of people who were sucessful.

What does she want to study?

NOt my DC, but I went to Oxford from a rough state comp in the Rhondda, two other people from my year went to Oxford the same year as me, and four the next year

Dh went to a state comp and he went to Oxford, as did our best man. His wife went to a state grammar school

Last year two of my students went, one to Oxford and one to Cambridge