So the edition I read only had the Dark Tower.
A "Radio parable play' which riffs on a combination of Browning's Childe Roland and 'Everyman' or 'Pilgrim's Progress'.
the opening announcement quotes Browning 'and yet/Dauntless the slughorn to my lips I set/ And blew "Childe Roland to the Dark Tower Came"' and makes the point 'Note well the words, 'and yet'. Roland did not have to-he did not wish to-and yet in the end he came to: The Dark Tower.'
As a reading of Browning this might rely too heavily on two words, but in MacNeice's version Roland, like all his family reaching back to George, has to travel on a quest to confront the dragon in the dark tower. He is trained for this from childhood, but isn't convinced it's what he wants to do, or even if it can be done.
The danger with parable and allegory, as MacNeice was well aware, is that they degenerate into a kind of unconvincing mechanical equivalence...Love=the girl, life=the quest etc etc....There has to be something more which makes the allegory stick in the reader's mind. Browning's Childe Roland works because while strongly suggesting that it "means" something it resists complete analysis. There's a powerful sense that the story is happening on the edges of one's vision rather than clearly in plain view.
MacNeice achieved much the same. He takes the parable, which reduced to prose would sound horribly banal, and allows it to escape from the algebraic confines of such thinking by presenting it as a dream. This means that significance is never simply this=that. This could represent a great deal of things, or just be itself. Mother is mother but Mothers, and the Sea Journey is a sea journey in a luxury liner complete with on board affair and dodgy steward and yet it could represent the real attractions of avoiding the dangers and discomforts of a task imposed by inheritance.
Obviously written to be heard, playing the tricks available (some of the scene shifts must have been very effective audibly, as when the Soax imagines a pub and the orchestra builds it for him) it still reads well.