Though it is only anecdotal evidence, I met a cop once who told me that it was not the job of the police to care whether a person was guilty or not. That was " the judges' job " . Needless to say, I find it a lot easier to understand why police brutality is so prevalent now.
This was in Canada, but I doubt that police culture, when you get down to essential elements, is that different in the two countries.
Not really as blunt as that, but my police officer friends more or less concur. The job of the police is to find who most likely commited the crime. The job of the prosecutor is the prove that likelihood. The job of the defense is to poke holes in that proof. The job of the judge is to wrangle cats.
I don't think they have a high appreciation of lawyer theatrics in front of judges.