copthall, your telegraph article describes considering whether a candidate was state or privately educated measure as needing to be reviewed - has it even been? Every year that is the figure that is reported in the press for oxbridge, usually with some degree of outrage that it has fallen short of their target figure (also often reported), so that is definitely the figure they have thus far been measured against, even if it's going to change soon.
For example: 2012 admissions:
"According to Cambridge, 63.3 per cent of British students admitted in 2012/13 are from state schools, compared with 58 per cent last year.
...
All universities are now expected to set targets to increase admissions among pupils from state schools or poor backgrounds in returning for charging up to £9,000 in fees. Cambridge?s state school target stands at between 61 and 63 per cent."
(from here)
Or 2010 admissions:
"The proportion of students from state schools offered places in 2010 was 59.3%, 0.8 percentage points up on 2009, according to the university.
But it was still below the 2008 figure and the university's 60-61% target."
(from here)
(Or this article.)
Also, research into admissions at Oxford university herehas shown bias towards state school applicants at the interview stage for marginal candidates as well as contextual stuff being used in shortlisting (this bias is justified in terms of later performance). The guardian artical is interesting, and shows how each candidate is inividually considered, but the oxford research shows how an individual speaking up for a candidate at such meetings can have a big impact on how opinions sway - unfortunately the presence of a journo may make a significant difference to when and how such individuals speak out. Even if it is an accurate relection it really doesn't show that there is or isn't a bias towards state educated pupils, it does that there is a good attempt to consider the whole picture for each candidate, not how succesful that is.
One quote from the Oxford research from a similar meeting shows how the state/private figures are on the minds of the selectors: "The selector remarked that, ?as an added bonus,? this applicant would count towards the subject?s state school intake because the student had changed from a private school to a state grammar school for the sixth form"