Before Paul Bailey became a novelist he embarked on an acting career. He seems to have been rehearsing the role of an old man for most of his life. Bailey's 1967 debut, At the Jerusalem, was written in his 20s but focused on an elderly heroine's journey from an old people's home to a lonely death in a mental ward. Old Soldiers, from 1980, featured two septuagenarians assailed by memories of the first world war; while Bailey's best-known work, the Booker-nominated Gabriel's Lament, features a wild eccentric who endures to the age of 94.

The creation of Harry Chapman  a former actor-turned-novelist who makes a youthful debut with a book about old age  suggests Bailey may have finally caught up with himself. Chapman has a fatalistic turn of mind ("It had been his habit, for at least a decade, to turn to the obituary pages first. He needed to know who was in and who was out"); and finds his worst fears realised when he lands in hospital with a tumour growing in his stomach. "So here he was at last, where he had long feared to be."

As might be expected from a narrative which remains confined to a hospital bed, not a great deal happens. Chapman recalls an upbringing of genteel poverty "in the shadow of the candle-factory and the gasworks"; and muses on figures such as his genial Aunt Rose, "a stranger to moodiness", his acerbic, self-centred lover Christopher, and the rich, compassionate childhood friend whose affluent Jewish family introduced him to Schubert and Babar the Elephant, thus setting his course for a life of the mind.

The tedium of life on the ward is alleviated by the nursing staff who provide an audience for Chapman's recitals of favourite poetry, and conversations with a young doctor who variously reminds him of a Filippo Lippi fresco and a Caravaggio fruit seller. Yet gradually the visitors to Chapman's bedside become increasingly bizarre: a Victorian dandy who introduces himself as Pip from Great Expectations and a woman in an empire-line dress who appears to be Jane Austen's Emma; followed by Dostoevsky's Prince Myshkin and Christopher Smart's meditative cat, Jeoffry.

These freewheeling literary hallucinations present a challenge  the reader is required to keep pace with a narrative which veers randomly from the thoughts of the 17th-century divine Jeremy Taylor (who described a hospital as "a map of the whole world") to visions of Fred Astaire dancing with Queen Celeste from the Babar stories. Yet it is accomplished with a wit, verve and economy which suggest the best ploy is simply to submit, as Chapman does, to the miasma of thoughts that flow through the mind while he is strapped to a gurney: "A new someone commented on his paleness to a new another, who responded that she'd seen more colour in an uncooked fillet of cod. If I ever get out of here, I shall use that remark one day, the novelist in him thought."

Perhaps the most significant of Chapman's fictional visitors is Melville's enigmatically obstinate clerk, Bartleby, who wastes away to nothing by declining all offers of assistance and even food with the repeated mantra: "I'd prefer not to". Chapman "had come to Bartleby late in life, and the skeletal clerk had been by his side ever since. He was still unsure, careful reader that he was, what the short, beautiful novel really meant. It refused to be summed up neatly, to be encapsulated in a paragraph or so."

Chapman surely speaks on behalf of his creator when he notes that his intellectual life has been "a voyage of discovery that could only end with his death. He read voraciously, then judiciously, and found his writing voice by rejecting the voices of those he was tempted to impersonate." Yet among all his influences, it is Bartleby that seems paramount. Refusal to conform is a kind of heroism that often goes unnoticed, yet like Melville's radically spare novella, Chapman's Odyssey is an enigmatic work whose meaning is worth grasping for. It is the kind of book that could be construed as a deeply moving, valedictory statement of a valuable career  though it would probably prefer not to.

From its title onwards, this attractive if slightly limp novel claims kinship with Paul Bailey's more robust exercises in male self-inquiry, Peter Smart's Confessions and Gabriel's Lament. It follows the same recipe of commotion recollected in tranquillity, but opts for the less intimate third-person and places as much emphasis on the circumstances of recollection as on the memories themselves, which once again relate to a grim upbringing in south London and the escape route offered by literature and music. The earlier heroes were named after tangential figures in literary history  Christopher Smart's father, Edmund Spenser's best friend  and while Harry Chapman in the new book has no such forebear, his surname enables the book's playful title. Chapman's Odyssey alludes to a famous translation (by George Chapman) that figured in yet another Bailey novel (Sugar Cane).

It also prompts memories of a famous poem, "On First Looking into Chapman's Homer", in which Keats celebrates the elating and transporting effects of literature. This is what Bailey aspires to do here, though his nerdish jokes make a stronger impression than his attempts at depicting and articulating Chapman's gratitude.

Harry is an elderly writer in hospital after a period of illness. During his stay he conjures up his saintly aunt and his reproving mother as well as people he never knew, such as Fred Astaire, and imaginary figures from his favourite books, including Melville's Bartleby, and Jane Austen's Emma. Between his nightly dream-memories and his waking exchanges with doctors and nurses, the book covers the social, sexual and professional high-points of his life, as well as hinting at "the blessed days, months and years when Harry Chapman did nothing more adventurous than reading and wondering"  his experiences as "a hero-worshipper of those who use words or notes or brushstrokes to convey something of the mystery and wonder of human existence".

Those phrases are typical of Bailey's verbal habits in this book, which tend towards cliche. Harry is visited by "Philip Pirrip, he of the great expectations", lies awake to the sound of "Mrs Stubbs, she of the moaning and the Brünnhilde shriek", and encounters "the wicked Maurice  he of the impossible positions". There is also a hefty helping of pedantry ("cathetered  if such a verb existed", "umpirical  was there such a word?") and allusion: "looked on the bright side when there was no brightness visible" (Milton), "alone and palely loitering in what appeared to be a limitless desert" (Keats), "Why, this was hell, nor was he out of it" (Marlowe).

Bailey has crowded this novel with words from elsewhere, even quoting whole poems in full, and at one point riffing on the opening sentence of Gabriel's Lament. It is unclear whether this is a case of an author who just cannot help himself, or of a novel, like Michael Cunningham's new study of a "corrupted imagination", By Nightfall, bent to the perspective of a character "never at a loss for a connection between literature and life". There is some supporting evidence for the second, more charitable view. Harry is incapable of talking to a doctor without telling him that he reminds him of a figure in a Renaissance fresco; he imagines Prince Myshkin at his funeral. But it is Bailey who places Harry in a ward named after a neo-classical painter (Johann Zoffany  discussed briefly in Gabriel's Lament) where he meets a former employee of Lloyd's who claims to be in possession of TS Eliot's false teeth. For every detail that suggests Harry is the narrow-minded obsessive, there is another that places the blame squarely at the author's feet.

But when he isn't oppressing the reader with little jokes and book-titles and famous poems, Bailey proves himself capable of imagining a busy mind caught between memory and dream. Towards the beginning, Harry sees himself as a schoolboy walking quickly home through a poisonous fog only to find that "number 94 and 98 stood next to each other, with nothing in between". And later he sits in the stands at Wimbledon watching a men's final in which the players keep on changing, so that a match opens with Roger Federer, continues with Jaroslav Drobny, Rod Laver, Ken Rosewall and Bill Tilden, before ending with John McEnroe.

Bailey's imagination, that amazing breeding-ground for image, anecdote, and caricature, is not as fecund as it once was. And where, in middle age, he was able to recover the spirit of past excitements, he now comes over all misty-eyed. But it is nevertheless a privilege to be in his company. His high spirits are infectious, and he is one of the few modern writers  the late Robertson Davies was another  who strives to emulate Dickens's mixture of comedy and pathos rather than simply being, in one broad feature or another, "Dickensian".