//Already I'm missing the original inept inspector .//
It depends who you mean by “the original inept inspector”, baz.
Tom Chambers (who appears in the latest episode) played Inspector Sullivan throughout series 2 and 3. He popped up again in one episode of series seven and once again in one episode of series eight (by which time he had been promoted to Chief Inspector). Now he’s back again (without any further promotion).
In series one Hugo Speer played the leading cop – Inspector Valentine. Jack Deam (playing Inspector Mallory - who was probably the most inept of the lot) did not appear until series four.