Prince Frederick of Sileasia (Garfield Morgan) has arrived in London for a three day visit.  Sileasia, a small country bordering Russia, is a potential political hotspot which would be ignited by Frederick’s assassination.  Cork is assigned the task of keeping him alive.

Prince Frederick is strong-willed and initially disdainful that he’s in any danger.  This is a dramatically obvious choice, as an unpredictable subject is much more interesting than a compliant one.  Morgan, a familiar television face (well known for playing Haskins in The Sweeney) gives an icy turn as the Prince.  It’s not the most nuanced of performances but as the episode progresses we do start to peel away the layers of Frederick, the man.

The studio-bound limitations of Cork are more evident in this story than some of the others – the first assassination attempt is a good example of this.  Frederick walks to the window and is lucky to avoid a rifle bullet.  After the shot is fired the camera focuses on nothing for a few seconds before we cut back to the action.  This was always a hazard of multi-camera studio recording – since editing had to be in done in real-time it was easy to miss something.  The small amount of recording time meant that retakes only tended to occur when something went dramatically wrong, so whilst this looks a little clunky it clearly wouldn’t have been judged important enough to merit recording the scene all over again.

At one point Cork mentions that he plans to consult the dynamite section.  Terrorist attacks with dynamite and other explosives weren’t uncommon during this period (see here for some real life examples) and The Case of the Persistent Assassin serves as a painless history lesson.

Frederick tells Cork that he wishes to return to his country and end the division and bloodshed.  Irene Stone (Liane Aukin) who attempted to blow him up with a bomb sees him in quite a different light.  “You butcher! You murdered my three brothers because they tried to speak against you. You put my mother and father in jail. You’ve turned Sileasia into a prison house!”  It’s quite telling that Frederick doesn’t attempt to contradict her – although it’s unlikely he would have recalled Irene’s family, he acknowledges that many innocent people have suffered in the past.  It does pose the question as to whether he’s quite the benefactor he claims to be – this is firmly answered at the conclusion of the story.

With Cork and Bob somewhat pushed into the background, this is one of the lesser episodes of the first series.  The telerecording is notable for a black blob that’s present during most of the episode.  It’s not quite as distracting as the fly that wanders across one of the telerecordings of The Avengers but it comes close.