The outgoing Metropolitan police commissioner, Dame Cressida Dick, has warned against the “politicisation of policing” as her tenure at the top of Britain’s biggest police force comes to an end. Dick was forced out as head of the Britain’s biggest police force after London’s Labour mayor, Sadiq Khan, accused her of failing to deal with a culture of misogyny and racism within the Met. In a farewell letter to London before her last day in post on Sunday, Dick said there was more she wished the force had achieved during her time at the top. But she added: “The current politicisation of policing is a threat not just to policing but to trust in the whole criminal justice system. Operational independence from local and central government is crucial for an effective democracy and is a model respected around the world. We must all treasure and protect it.” The letter was published shortly after Khan took a final swipe at the commissioner, telling a Labour local election event he would not “hide from the fact that I lost confidence in her”. Khan’s confidence in Dick reached breaking point when a scandal emerged at Charing Cross police station, where officers were found to have shared racist, sexist, misogynist and Islamophobic messages. Two of the officers investigated were promoted, while nine were left to continue serving. The Met leadership’s handling of the murder of Sarah Everard in March 2021 by a serving Met officer also caused consternation in City Hall and government. After her killer was sentenced to a whole-life term in September 2021, the Met leadership was expected to show it understood those concerns. Instead, it was mocked after saying that women who were worried about an officer approaching them could wave down a bus. Since her departure was announced, judges have ruled that the Met breached the rights of the organisers of a vigil for Everard with its handling of the planned event. In the letter, published on Friday afternoon, she said: “We hear the criticism, know not everyone has confidence in us to provide a good service when they need us, and have seen among us those whose horrific actions have let you all, and us, down so terribly. “Each one drives us to get better, to root out those who don’t uphold our standards and don’t deserve to wear our uniform. To improve our response so all our communities feel protected by us. “We are listening and acting on what you tell us so we can change for the better. Just this week we launched our violence against women and girls plan, shaped by the views of hundreds of Londoners.” Dick, the first female leader in the Met’s 193-year history, has led the force since 2017, with her original five-year term as commissioner due to end in April this year. Her contract was extended by two years to 2024 only last September​ by the home secretary, Priti Patel, which Khan endorsed. But Whitehall sources made clear that if Dick lost the confidence of the mayor they would not fight to save her. From Sunday, she will take unused annual leave, with her final day of employment being 24 April. She was met with applause and cheers of “hip, hip, hooray” as she walked through a guard of honour outside Scotland Yard ahead of her last day in the job this weekend. Walking down the steps of the force headquarters and in between two lines of uniformed officers on Friday, she was greeted with salutes, which she returned before saying “thank you very much.” Deputy commissioner Sir Stephen House will temporarily serve as acting commissioner while the recruitment process continues.