This morning's revelations in the Guardian that Rupert Murdoch's newspaper group paid out more than £1 million to settle legal cases that might have exposed criminal activity by News of the World reporters turn the spotlight once again on the Metropolitan Police Service and Mayor Johnson's relationship with it.
The vagueness and complexity of this was again exposed this morning when Boris was ambushed during a Today programme interview that was initially about EU regulation of financial services before questioning switched to how he would respond the Guardian's story in his role as chair of the Metropolitan Police Authority, whose job is to hold the MPS to account.
If you listen again from 07:22 you'll hear Boris first protest that he'd been "wholly engrossed in financial services" and therefore not yet read the Guardian, before being told that he was among those whose privacy was apparently invaded by private investigators working for the NoW.
He was then asked if in his role as MPA chair he would be asking the police to investigate the matters raised. He replied:
Well, obviously as chairman of the MPA it wouldn't be right for me to intervene at all in any operational decision they might make.
This was the right answer, one from which I derived a certain tender pleasure in view of Boris's rather spectacular intervention in the Damian Green affair, one deemed "extraordinary and unwise" by a subsequent Standards Committee investigation. It was then put to Boris that his MPA duties made it "beholden on you, if there are allegations that the Metropolitan Police has evidence, which the Guardian says..."
Boris interrupted at that point, saying that he was sure that Commissioner Sir Paul Stephenson "would go ahead, go through the proper procedures and decide whether he needs to take action."
This, perhaps, was not quite the right answer. Or perhaps it was more of a Mayor's answer than that of a MPA chair's. In his capacity as Mayor it is OK for Boris to express confidence in Sir Paul. In his capacity as MPA chair, it feels a bit like he's trying to close down discussion or scrutiny. Was he claiming, asked the Beeb, that making sure that serious allegations are investigated is "not your business?"
Boris reiterated that he was sure the Met would "do the right thing" and did not rise to a suggestion that he might put in a quick call to Sir Paul and get back to Today a bit later. He was quite sure that the Commissioner would learn all he needed to know from the Guardian without any help from him. That may be so, but the constitutional confusion surrounding the Mayoralty, the Met and the MPA remains.
That is not by any means all Boris's fault. But can he really be the Met's supporter with his Mayor's hat on and its scrutineer when he dons his MPA one? Should any Mayor really be the MPA chair too?