I was a colonial police officer for 18 years, and all our vehicles  were checked by the driver before each shift took them over, failure to do so was a disciplinary offence, any faults were duly noted on the check sheets. Member i/c stations carried out ad hoc checks to ensure this was complied with.
The british police force used to have a great rep, now they are distrusted by the public, inefficent, and are to a large extent I believe, completely unsupported by the govts of the day, They appear, from what I have seen, to have no initial crime scene preservation techniques, due to a lack of interest or training,of todays officers.
I am of the opinion until they go back to not becoming so personally involved in their cases they will continue to suffer.. investigate, arrest, present the evidence for, and against, then its up to the courts, Police always are supposed to present the facts both Good and Bad with equality, unfortunately now days they only present the facts likely to gain a conviction, irrespective of whether the accused is guilty or not, and most of those so called cicumstantial facts are biased due to what the investigating officers "thinks" happened, as opposed to what he can actually prove happened.   I often wonder how many deserving offenders get away or receive too lenient a sentence from the Courts due to the probabilty that the Courts no longer trust the police evidence that is presented to them as they used to, particularly when it consists of mainly circumstanial evedience..