By Ian Dunt Follow @IanDunt
Boris Johnson shouted at several journalists today during an extraordinary press conference where he faced questions about why he failed to take phone-hacking seriously.
The London mayor cut a nervous and uncertain figure as he announced the resignation of Sir Paul Stephenson and John Yates at City Hall.
He was repeatedly asked about why he had dismissed the phone-hacking scandal in 2010 as "codswallop" and part of a Labour conspiracy.
At one point the mayor shouted "I am accountable" to a question from a reporter, before cutting short another's line of questioning with: "That's why we're having an investigation".
Mr Johnson's prickly disposition reflects the tension felt across London at a political scandal which is now out of anyone's control.
When asked why he had not taken phone-hacking more seriously when the Guardian began publishing details of systematic malpractise at the News of the World, Mr Johnson insisted that he had come to his conclusions on the back of advice from assistant commissioner Mr Yates, who had resigned moments earlier.
"I did enter a very import caveat when I used that admittedly colourful provocation," Mr Johnson said.
"Ok, I misunderstood the severity of the allegations but that was actually because no-one had briefed me about what was in the rubbish sacks [the three bin bags of evidence retrieved from private investigator Glenn Mulcaire which contained details of thousands of phone-hacking victims]."
He added: "I had a very, very clear briefing from the police, from John, that there was nothing new in these allegations.
"It struck me that if he said there was nothing new that was good enough for me.
"It's not my role, it's not my function to say 'go back, have another look'. The mayor does not have operational management of policing."
The press conference came as the phone-hacking scandal hit the police, prompting the resignation of the commissioner and assistant commissioner.