Yes I used to work for one of the largest employer of graduates in the UK and we looked at this.

Equal opportunities is about not discriminating on the basis of gender, race or disability. Also various bits of legislation also prohibit discrimination on the basis of financial status, nationality, religious or political beliefs and sexual orientation (although these don't normally come under the "equal opportunities" banner).

You can legally use performance correlation in hiring (people who went to X tend to do well, so we'll prefer to hire people who went to X), as long as it doesn't violate one of the legislated areas. In the legislated areas you can only discriminate on where there's evidence for a link. So for example you can favour Computer Science students for Developer jobs over non-CS students even though that contains an implicit gender bias.