Coming back to the 'Yardie" question — it is a convention of the English detective novel that the local force will generally resent their Chief Constable's decision to 'call in the Yard', as a vote of no-confidence in their own ability to solve the case; esp, as would appear to be the case here in the eyes of Superintendent Dalziel & Inspector Pascoe [or whatever ranks they may have achieved in this particular novel], the incomer is often represented as officious, patronising, and self-important (all attributes subsumed in that meaningful adjective 'jumped-up').