HMRC 'briefing' Osborne

I note in the news today that "Ostrich" Osborne is "shocked" that the wealthiest individuals in the UK only pay a marginal rate of tax of about 10%, he having been plied with anonymised tax returns of some of our wealthiest by HMRC.  Leaving aside how "shocked" I am that this comes as a surprise to him, I would be interested to know whether he or his department asked for this information or, on the other hand, whether HMRC decided unprompted to volunteer it.  The wording in the news suggests the latter, although it is not conclusive.  But if so, it begs the question, what business is it of HMRC to draw Osborne's specific attention to the fact that a handful of citizens are paying the "right amount of tax" according to the laws that they, as civil servants, have been instructed to implement by their political masters?  Or does HMRC in reality have a secret political agenda to maximise the revenue collected, despite its repeated reassurances to the public that it is only interested in collecting the right amount of tax?