Bit of a resurection http://www.bbc.co.uk/news/education-12499265
"David Willetts has warned that there will be more cuts to higher education if too many universities opt to charge maximum tuition fees"
So uni's can charge up to £9000 if they meet the criteria but if the average charge (across all uni's) goes above £7500 then they all face more cuts, which is why the need to charge so much in the first place (£7000 just to cover the initial cuts). Doesn't seem like they thought this through.
Sounds like a classic prisoner's dilemma.