A good use of "big data"

And finally a good example of the use of "big data" to answer social scientific questions that someone actually cares about. This IFS study by Britton, Shephard and Vignoles uses matched HMRC data on earnings and Student Loan Company data on graduates to provide better estimates of the gap between graduate and non-graduate earnings than have heretofore been possible. The full paper is here and very worth reading. 

Now then UCAS, if HMRC and SLC can allow administrative data to be linked and then make it available to academic researchers investigating a matter of clear public interest why can't you do the same with your administrative data?