While the Complete University Guide subject tables are useful, please don't just look at the overall score! Also look carefully at what information constitutes the tables.
For example, the Entry Standards score is the average UCAS tariff score of new undergraduate students NOT the grades equivalent of the standard offer for the course. This includes the UCAS points derived from drama/music and dance exams for example.
Some of the universities with the highest proportion of independent school students (Oxford, Cambridge, Durham, Imperial, St.Andrews, Bristol, Edinburgh, UCL, LSE, Exeter, Bath etc) always typically occupy some of the top slots, but their ranking may well be bolstered by privately educated students who arrive with their Grade 8 music, Lamda, ballet, drama and horse-riding qualifications!
Click on the columns for Research Quality and Graduate Prospects to get a much more reliable reflection of the quality of a course (and a slightly different mix of 'best' universities).
For example, York has an excellent reputation for Computer Science. It's one of the uni's biggest departments, has had masses of investment and is top ten for its research quality and also graduate placement, as all its courses offer a year in industry option.
Universities such as Durham, Exeter, Bristol etc sometimes fall much lower down the list on research.