The career of Sir Ian Blair has long been something of a puzzle. The consensus is that the former Metropolitan Police Commissioner was the quintessential "political" copper, sucking up to Labour ministers. And there was plenty of evidence to support this in the form of Sir Ian's open support for the Government's ID cards legislation and his active lobbying of MPs in favour of 90-day detention.
But then came the cash for honours investigation. As my colleague, John Rentoul, has pointed out, Sir Ian wasn't Tony Blair's favourite policeman after that episode. So how did he go from ministerial toady, to fearless upholder of the law? And why?
At the weekend Tarique Ghaffur, also late of the Met, had an explanation : "The [cash for honours] inquiry gave him [Blair] leverage over the Home Office. He needed its ongoing support as he dealt with the aftermath of the de Menezes affair and, with cash for honours hanging over the Government for a year or more, nobody in Whitehall would want to antagonise him." So the de Menezes disaster was what changed everything. Sir Ian didn't suddenly become apolitical over cash for honours; he was playing a political game for his own survival.
Now Ghaffur is obviously not an objective source, having taken the Met and Sir Ian to an employment tribunal, accusing them of racism. But his analysis would certainly make sense of Sir Ian Blair's switchback relations with his political masters.