Former Met Assistant Commissioner Neil Basu doesn't believe the appeal of policing to individuals like Wayne Couzens or David Carrick is 'properly understood' within the service.

Policing has to "answer three fundamental questions" to understand how individuals such as Wayne Couzens and David Carrick managed to join and remain in the service.

Referring to both men as "monsters", former Met Assistant Commissioner Neil Basu said in an interview with Crest Advisory: "How could they survive in policing?

"How do you think that happened, that all those opportunities - particularly with Carrick - were missed?"

According to Mr Basu, the service needs to understand why the  profession attracts individuals with twisted motivations.

He said: "If you're gonna' give somebody enormous power over somebody, and the uniform, and you can allow them the independence to work on their own, you could potentially have a problem. 

"So do something about your recruitment and make sure you don't recruit them."

Mr Basu also says the service needs to be better at identifying the warning signs once a person is in post.

Citing a number of examples of "red flag behaviour", he asked: "How good is your policing system, your professionalism, your ethics, your standards, at picking that up and dealing with it quickly?

"I would argue not very good at all."

The third question policing must answer centres around culture; specifically, what is the approach to calling out misconduct and how can this be instilled in forces of varying sizes.

According to Mr Basu, acknowledging these issues does not diminish the fact that he has worked with tens of thousands of police officers who "really are the best of us".

However, that's not where an officer's responsibility ends.

He said: "Every single one of those brilliant, brilliant police officers needs to understand they have a responsibility in their culture to call out all of the bad ones, long before they commit some heinous crime.

"But they should be calling out that lack of professional standards. Does policing have a culture that does that routinely? How do you instil that?"

Addressing the challenge facing Commissioner Sir Mark Rowley as he bids to reverse the Met's fortunes, Mr Basu admitted that it's "probably easier" to instil the correct culture in a smaller force.

However, he thinks "both have their complications".

The merits of stop and search and neighbourhood policing were among the other subjects discussed in the wide-ranging interview.

On the former, Mr Basu said: "I've seen no professional evidence to say that stop and search as an effective crime tool."

He does, however, think that chief constables - aided by strong political backing - are "addicted to the idea that stop and search is solving a problem".