Wordsworth, in the essay "Supplementary to the Preface to the Lyrical Ballads", reminds us that "every author, as far as he is great and at the same time original, has had the task of creating the taste by which he is to be enjoyed: so has it been, so will it continue to be." With A Cruel Bird Came to the Nest and Looked In, his seventh novel, Magnus Mills continues the apparently never-ending task of teaching readers how to enjoy him.

It's quite a job. Because, we should admit it, Mills is not always an easy writer to enjoy. He's an easy writer to admire, of course, but that's different. We might admire Beckett's novels, but we don't necessarily enjoy them. Do we? Mills is admirable in the same way that Beckett is admirable. He has the courage of his convictions. Which can make him seem sometimes odd, cold, and displeasing, with a deficit of affect, though perhaps "dry" would be a better word than "cold". Mills once remarked in an interview: "I can't tell which bits are funny. I just put dry things in." His work occupies the very outermost regions, the semi-desert distant steppes of what we usually think of as the declared realm of the novel, which is why he is sometimes compared to Beckett, or to Kafka, or Calvino, outliers all, though in A Cruel Bird he comes closest in fact to the territory of another great literary outsider, Mervyn Peake.

One might go so far as to argue, on the evidence of the latest novel, that Mills is constructing his own vast, sprawling Gormenghast, adding towers and escarpments to his extraordinary earldom, brick by brick, and book by book. All Quiet on the Orient Express (1999) was a recapitulation of the themes in his Booker-nominated first novel, The Restraint of Beasts (1998). And The Scheme for Full Employment (2003), Explorers of the New Century (2005), and The Maintenance of Headway (2009) have played basically the same delightful games and tunes around and about the nature of work, and about organisations, and about human systems. Fantasy literature is one way of describing it, as long as your definition of fantasy literature includes not only Peake, but also Tristram Shandy, the work of Bruno Schulz, and Gombrowicz's Ferdyduke.

Mills has not only his persistent themes, but also his persistent kinds of characters, with whom he perpetually tinkers: there is usually a naive narrator, caught up in some sort of pointless toil with a small group of earnest eccentrics who talk to each other continually at cross-purposes. His consistency of purpose as an author might be described negatively as a kind of pathology, a form of self-plagiarism almost, or it might, on the other hand, be praised as a form of profound attention, and a sign of true greatness. It all depends on the quality of the tinkering. And the nature of the work being tinkered with.

Fortunately, A Cruel Bird is as utterly odd, as endearing and as disturbing a book as anything that has come before. The novel's unnamed narrator is the principal composer to the imperial court of a place called Greater Fallowfields, which bears about as much and as little resemblance to anywhere in the actual world as any of Mills' places and locations  it is the world, but the world abridged, stripped and removed of irrelevant detail. The concert hall, for example, the most famous landmark in Fallowfields, and known as the "cake", is described in deliciously vague fairy-tale terms. "Constructed in the days when the empire was at its zenith, the cake was built from a very rare kind of stone, quarried to specification in a faraway land and ferried home in ships."

The plot is similarly indistinct  and, thus, vaguely and impressively massive. In the absence of his exalted highness, the majestic emperor of the realms, dominions, colonies and commonwealth of Greater Fallowfields, the narrator has been left to run the affairs of state, along with Brambling (chancellor of the exchequer), Garganey (postmaster general), Whimbrel (astronomer royal), Sanderling (comptroller for the admiralty), Dotterel (suveryor of the imperial works), Wryneck (pellitory-of-the-wall), and Smew (librarian-in-chief). With very little actual work to do, they are involved in never-ending discussions and wrangling over procedure. As characters they are almost indistinguishable one from another, apart from their names, and so exist only in dialogue, in relationship, and in action. Everything in the book is conspiracy, rivalry, ritual, and the quest for power, particularly after a gang of men from a neighbouring principality are discovered building a railway headed straight for the emperor's court.

"It's all jumbled and disorganised," remarks the narrator on the empire of Fallowfields, "we have a vast hierarchy with serfs at the bottom and the emperor at the top, but in between there exists a pecking order that's vague and unfathomable to say the least." The wonderful thing about the outlandish world of Magnus Mills is that it always sounds familiar.

Ian Sansom's Mobile Library series is published by Fourth Estate.