I have had several run throughs of both series of Special Branch before, but have tended to miss something in this episode. I feel like the stakeout is a standard dramatic set up for the crime shows of the seventies - dramatically it allows character development, allows for an exciting denouement and must be relatively cheap. The only difficulty is preventing boredom settling in and that is usually done by the interplay between the (invariably two) officers doing the stake out. Unfortunately they didn't have the ultimate resort of a totally weird event used by Scully and Mulder while they were being punished by the FBI in later series.
In this episode the development used to distract from the ennui is the friction between Haggerty and Craven, which in fact dominates the whole episode. This is an entirely personal view because as regular readers know I prefer my TV unreal, but the ongoing friction doesn't really do it for me. This is purely because situations where you can't concentrate on the matter in hand because of something extraneous interfering, really irritate me. The problem with the argument is that Haggerty is what my mother (and probably Craven) would describe as 'a sexy piece'. By this I mean that he is perceived to be overly sexy but isn't really. Extra depth to the argument is given by the fact that Haggerty doesn't even know he supposedly broke up Craven's marriage and Craven is depicted behaving to his girlfriend in a way which would nowadays be seen as crossing over into coercion and control.
The conflict made me rather let the show wash over me to the extent that I completely missed the role played by Dame Hilda Bracket (billed as she often was in the seventies as Perri Sinclair) singing in a club and then Craven asks her to spread a rumour for him. She had not long appeared in one of the Steptoe films and I think these appearances say all there is to say about the seventies. Also I do love the way she gets her bum pinched after being helped off the stage.
When the denouement comes it comes very quickly and there is the twist that Haggerty gets promoted to Craven's very obvious displeasure.