Met police investigate claim of 'pleb' row conspiracy against Andrew Mitchell CCTV footage shows the then Conservative chief whip, Andrew Mitchell, leaving Downing Street through the side gate Link to this video Scotland Yard has said it is considering the possibility there was a conspiracy to fabricate evidence against the former chief whip Andrew Mitchell, insisting its inquiry would go "where the evidence takes us." The Metropolitan police vowed to get to the truth after No 10 told them to "get to the bottom" of the "exceptionally serious" allegation that a serving police officer fabricated evidence that led to Mitchell's resignation in October. Scotland Yard, in a statement issued on Wednesday, said the allegation went "to the very heart of the public's trust in the police service." If any evidence emerges of conspiracy this will form part of the investigation. Mitchell was forced to resign after the police log and an email by an unnamed officer suggested he had called police officers "fucking plebs" when they declined to let him wheel his bicycle through the Downing Street gates. In an extraordinary twist to the story, which No 10 sources insisted was entirely coincidental, the police officer - the "witness" - emailed his account of the incident to his local MP, John Randall, who was then Mitchell's deputy in the whips' office. Channel 4 said the police officer was also one of Randall's constituents. In its statement, Scotland Yard stated: "The Metropolitan Police Service is conducting a thorough and well-resourced investigation to get to the truth of the matter as quickly as possible. Since receiving fresh information last Thursday, the MPS has acted swiftly. On Saturday, an investigation into the alleged unauthorised disclosure of information was reopened. On Saturday evening, an officer was arrested on suspicion of misconduct in public office. On Sunday, the investigation was referred to the IPCC for supervision. The investigation is looking at the alleged unauthorised disclosure of information and the circumstances surrounding a police officer's claim to have witnessed an incident in Downing Street. This is a fast-moving and comprehensive investigation and the highly unusual events of the last three days have shown this inquiry will need to go where the evidence takes us as it progresses. The former shadow home secretary David Davis said he had seen emails that clearly showed a police officer had "masqueraded" as a civilian and acted in a way that "effectively completely undermined" Mitchell in the eyes of the prime minister, who then had to decide what to do. He told the BBC Radio 4 Today programme: "That explains quite a lot of the, frankly what appears to be, with hindsight, daft decisions, in terms of the way they handled the whole issue." Davis criticised the cabinet secretary, Jeremy Heywood, for failing to check who had sent the email. Bear in mind there was a cabinet secretary who investigated this and clearly did not check who the individual who sent the email was, given that he gave his own name, though we can't use his name. None of this, whether it's the Met investigation or Jeremy Heywood, none of it's exactly Sherlock Holmes. I think all investigations did not go to the heart of it. Look at the CCTV footage, see whether it's consistent with the allegations, what's been said - you can't draw conclusions from it, because it's very low resolution, but it clearly wasn't. He said the Met chief Bernard Hogan-Howe needed to ask whether the motive for the officer's actions was money, politics or "trying to help out some friends." Davis said: "How did he get the information that propped it up? [The email is] virtually identical [to the log]. Did he collude with anybody else, was he in communication with the original officer? On Mitchell's future, Davis added: "He was forced to go by a combination of events, which started with Downing Street's reaction as a result of the email. As a result we've had a serious injustice. He should be returned to high office. He was a fantastic international development secretary. He probably will not become chief whip again but I think the injustice should be put right. The national police federation said the arrest of a serving police officer and the ongoing inquiry was a "separate issue to the original claims made by the Metropolitan police officers as to their treatment by a serving MP." The federation suggested a full investigation of the incident should have taken place at the time it emerged in September. "It is disappointing that all information and evidence regarding the original incident was not revealed at the time - if that had occurred perhaps we would not be in the situation we now find ourselves in as a police service," the federation said in a statement.