After the murder of Sarah Everard by Wayne Couzens, I have come to the conclusion that Cressida Dick needs to go. Yes, it’s easy to call for the resignation of a Metropolitan Police Commissioner. Things go wrong in the policing of London and when the mistakes are big enough, there will be calls for heads to roll. Often, such calls are just another way of expressing anger. But not only has Cressida Dick failed to produce tangible improvements over the past four years: under her tenure, things have become significantly worse.

I was a police officer for 30 years and I’m afraid there is much truth in what critics of the police say. The problem exposed by Couzens is not confined to a few rogue officers. The Met is still stained by racism and misogyny; Cressida Dick may have begun her career determined to change this, but somewhere along the way she has given up.

The culture is at its worst in specialist groups like the Parliamentary and Diplomatic Protection (PaDP) branch. Units of this nature have a sub-culture with fewer checks and balances. In the borough-based uniform units, offensive language is less tolerated. In the specialist groups, a laddish culture develops. ‘If you can’t take a joke, you shouldn’t have joined,’ they say.

Their banter has licence to be sexist, racist and homophobic because the supervisors don’t challenge it. Many of them are afraid of the career constables who intimidate them. When supervisors are too anxious to reprimand their subordinates, it creates a safe haven for sexual predators and other extreme and criminal behaviour. A few years ago, steps were taken to reform the PaDP but they were not carried out fully because the long-standing officers objected to them.

The disastrous failure to vet Couzens has been much discussed, but it is just as worry-ing that he found kindred spirits inside the force. A recent Freedom of Information request revealed that 26 of his Met colleagues have committed sex crimes since 2016. Their offences include rape, possessing indecent images of children and voyeurism. Five have carried out sex offences while on duty.

Earlier this month, another PaDP officer was charged with rape and remanded in custody, due to the seriousness of the allegation. These are not isolated incidents, as Cressida Dick and her supporters would like us to believe. And the crimes themselves are not independent of the culture in which they occur. Couzens was known as ‘The Rapist’ by some of his former colleagues. What does this tell us about police culture?

Cressida Dick now promises to root out ‘predatory’ rogue officers — but they shouldn’t be in the police force in the first place. The Met needs a more robust recruitment and vetting process in order to prevent these types of people becoming officers.

I’ve known her for more than 20 years and she is simply not the right person to oversee this reform. There was a time when she seemed to understand the challenges the Met faces, especially when we dealt with some sensitive equality and equity issues. I welcomed her appointment because I believed she was committed to changing the culture. But she has proved incapable at best — and disingenuous at worst.

On the Couzens case, her inaction has been inexcusable. Seven months have now passed since he was charged. You would have thought the very first thing a Commissioner and her management board would have done would be to devise and sign off a strategy to reassure women and girls that the Met was dealing with institutional sexism and misogyny; and to instruct male officers on how they should conduct themselves. At the stroke of a pen, the Commissioner could have ordered a significant number of plain-clothes officers to get back in uniform to reduce the risks of confrontation, without affecting their operational capability.

Instead, the Met has suggested that it’s up to members of the public to spot rogue police officers. We can’t discount the possibility that there are others like Couzens. Even the Met seems to be admitting this.

Cressida Dick has taken her eye off the ball. The recent decision to extend her job by two years was a missed opportunity to enforce change the Met so badly needs.