Superintendent Mullett appears to be using D. I. Jack Frost as some form of Guinea pig to test approved police quotas, and he has yet another work colleague to accompany him a D. C. Carl Tanner.
Denton Nick is replete with crime including cash and carry burglaries, with some stolen goods turning up on the East Dean sink estate, D. I. Jack Frost has a long term informant Natalie Bell living on the estate, who dies in her flat when it's deliberately set on fire.
Reading reviews of this episode makes me think that it would be so easy to pick holes in British detective shows for the lack of ethnic diversity, possibly unlike our transatlantic cousins who seemingly ensure, that they scrupulously tick every available box.
Indeed thinking it over I came to a similar conclusion as most detective series on TV in the UK are predominately white, the detectives and old bill are invariably caucasian as are any people appearing in them such as neighbours etc.
While culprits are a mixed bag depending on where they reside, invariably there may be a 'troubled area' or sink estate and as in this episode of Frost, there may well be black or either mixed race people being suspected of petty crime.