It starts very good cos of the brilliant chemistry between the two leads until one of the 'leads' disappears so does other interesting characters and later on when the show turns to just 'Miss Scarlet' it ends up nowhere turning into a generic period cop/procedural show. The new lead character is dull, boring and brings nothing new to the show.
As long as 'the Duke' (as well as Moses, Solomon and that filthy journalist etc.) were there it was very interesting, don't know who thought it would be a good idea to remove all the interesting and colourfil bits out !