Chris Mason: PM facing awkward hours ahead as Mandelson questions remain

Chris Mason: PM facing awkward hours ahead as Mandelson questions remain12 minutes agoShareSaveAdd as preferred on GoogleChris MasonPolitical editorAFP via Getty ImagesI occasionally like to kid myself that after 20-plus years of reporting from Westminster, I can't be entirely surprised any more.Then, along came the row of the last few days after The Guardian's revelations about Lord Mandelson, his vetting and the removal of the most senior civil servant at the Foreign Office, Sir Olly Robbins.It all prompted a one-word question from many of us: how?How could so senior a civil servant be in possession of such apparently politically explosive information and not pass it on to the prime minister and others?And how could a prime minister, embarking on a high-profile and controversial appointment, be so insufficiently curious that he didn't prise this information out of the government machine?Context is key here: in January of last year, Sir Olly had just arrived at the Foreign Office as its permanent under-secretary.Weeks before, his predecessor, Sir Philip Barton, had worked through the formal niceties of confirming Lord Mandelson's appointment to Washington, such as writing to the King about it on the 18th of December.In other words, it was a done deal. We already know some vetting issues had already been raised with the prime minister, but Whitehall, the civil service, knew of Sir Keir Starmer's wishes. So perhaps there was a sense that the security vetting didn't reveal much more than was already known, convention said it shouldn't be passed on anyway, plus it was too late.This would appear to be the bones of the argument Sir Olly will use publicly when he appears before the Foreign Affairs Select Committee.Getty ImagesSir Olly Robbins was the senior civil servant at the Foreign OfficeAnd this is where we get to the pointy headed end of this row: a debate about the meaning of the Constitutional Reform and Governance Act 2010.It st...