Andrew Mitchell 'has no confidence in Met Police Chief' According to The Times Mr Mitchell sought assurances that Mr Hogan-Howe would not be leading the investigation into the incident. Senior government sources believe Mr Mitchell's prospects have improved significantly, potentially opening the door for a return to the Cabinet. Asked if Mr Mitchell can make a comeback, David Cameron said: "One step at a time. Let's get to the truth about what happened but I think it has been an extraordinary development to find a police officer apparently posing as a member of the public, pretending to have been outside Downing Street at the time and then trying to blacken the name of a Cabinet minister. The suspect arrested yesterday was held on suspicion of "intentionally encouraging or assisting the commission of an indictable offence" - understood to be misconduct in public office. He was released on police bail yesterday. The Met has launched an internal inquiry into the matter, staffed by 30 officers. Mr Hogan Howe is now said to be on holiday until mid-January, by which time the inquiry is expected to be over. But the questions about his impartiality will deepen the gulf of trust that has emerged between the Conservatives and the police over the affair. The Police Federation, which has since been accused of orchestrating a campaign against Mr Mitchell, said last night that it would apologise if all the allegations against him were proven to be fabricated. Last Thursday a 52-year-old officer, a member of the Metropolitan Police's diplomatic protection group, was contacted by a journalist from Channel 4"s Dispatches. He was questioned about his claims that he had witnessed the exchange in Downing Street between Mr Mitchell and two armed officers. The officer allegedly emailed his local MP, the deputy chief whip John Randall, posing as a member of the public and corroborated newspaper claims that Mr Mitchell had sworn at police and called them "plebs." Mr Mitchell admitted swearing and apologised, but he has always vehemently denied using the word "plebs." Three weeks after the incident, with pressure mounting, he stepped down from his Cabinet post. Last Saturday at 8.15pm, the officer was arrested at his home in Ruislip, north-west London, and questioned on suspicion of misconduct in public office. He was released on police bail on Sunday and has been suspended from his post while inquiries continue. The officer is due to answer police bail next month. Scotland Yard said the second arrest did not involve a police officer or a member of police staff and his connection with the arrested officer is not clear. On Wednesday Scotland Yard said it was expanding the terms of its investigation to examine how details of a police log came to be leaked to two newspapers, including The Daily Telegraph.