Some of the questions raised in episode 3 are (sort of) answered in this episode, at least in terms of what the hell is going on.
Once again the episode is a superb vehicle for Steel - although I feel Sapphire gets more of a look in than she did in episode 3. The function of his rational hard-nosed personality in Sapphire & Steel's work is revealed: he is there to have the wit to reject dodgy appeals from dead people! I've actually just realised that Sapphire & Steel are both wearing evening dress - perhaps the powers that be in their world don't get the wardrobe quite right, in the way Steel is usually out of synch with mores & customs. Sapphire is almost accusing when she says to him, 'You're enjoying this, aren't you,' & of course he responds that he is.
What I like most about this episode is that it reaches an almost farcical level, parodying humans' attempts at contacting the dead. The seance is the point at which this reaches it's peak: it is reminiscent of the film Blithe Spirit, where an author thinks he will get a medium to provide material for his book, & pokes endless fun at her. In this context Steel just does not stop making fun of Tully & his methods. I particularly love this exchange:
Steel [watching Tully putting on a cross]: 'What's that supposed to do?'
Tully: 'Make me feel better... Hands on the tabletop please... Now we join hands.'
Steel: 'Is this important?'
Tully: 'It's vital.'
Steel: 'And how did you manage when you had a one-man sitting?'
Tully: 'Well, I just held my own hand.'
It is interesting therefore that Steel wants to try doing this Tully's way (& against his better judgement): I don't think it is necessarily contradictory, since it is plain that they have to find out what the craic is for the ghosts, & their methods so far have failed. What is clear is that it is Sapphire's 'mediumship' that attains contact, & that while Steel holds no credence in Tully's human religion & psychical investigation, these methods seem to work here. An unusual streak of humility in Steel here, although it could just be using the necessary methods to reach the desired end. Perhaps it is even that these are the methods the ghosts need to speak through.
The 'seance' scene also allows the narrative to return to Sapphire's narration, with just music to accompany it. This, to my mind is much more effective than the scenes in the last episode of thrusting the characters into the historical incidents. It's so effective in fact, it even makes a ghost go 'No!'