Why didn't Henry James have sex? That is the central concern of this engaging portrait of the fastidious master of verbose prose. It is also its fundamental flaw. For while Lodge staunchly insists that what he has produced is a novel, it's actually more of a tribute than a story and — far more hazardously — it's a tribute with a decidedly devotional undertow. The screw turns around two of James' most intimate relationships — with the American writer Constance Fenimore Woolson and with the Punch illustrator George Du Maurier, who later makes his name as the author of the phenomenally successful novel Trilby.

George and Constance are fully realised, complex characters. But they are also highly symbolic representations of those aspects of himself that James must suppress and forego in order to pursue a higher calling. George, with his boisterous brood of children and devoted wife, is the artist constantly compromised by the demands and duties of family life. Constance, his closest female confidante, is a woman he might have loved. And it is Constance who accuses him of portraying women as the enemies of art.

We are told from the start that James is a confirmed bachelor. "The reasons were complex and he did not care to probe them too deeply even in self–communing. It was enough to tell himself that his pursuit of literary greatness was incompatible with the obligations of marriage. He needed to be free, free to be selfish — that is to say, selflessly committed to his art."

Reflecting on his lack of libido, James comes close to acknowledging that his devotion to his writing might occasionally be a cover for less noble motives. Lodge portrays him as recoiling from the very idea of the mingling of juices and the fusing of flesh, despite allowing us a somewhat unconvincing glimpse of his lascivious fantasy for George's eldest daughter. At another point there's a very faint suggestion that he may be repressing a tendency towards men. More consistent and more probable is the account of James as a man simply too self–protective and too buttoned–up to allow for the possibility of abandon.

But these are distractions from Lodge's main theme: the irresistible parallels between James's celibacy and the constraints of the religious life.

James has to set himself apart from other mortals and purify himself from normal appetites in order to perfect his art. Like a priest who must give counsel without experience, he is haunted by Constance's remark in an early assessment of his work that he lacks "the genuine story–telling gift".

Given the pitiful sales of even his better–received works, her analysis appears prescient. Portrait of a Lady only managed a sale of 8,000, while Constance's East Angels exceeded 40,000. And Du Maurier, a lesser writer leading a much fuller life, broke all records when Trilby turned into a cult book and grossed close to a million sales.

Disillusioned by the indifferent performance of his novels, James attempts to become a playwright. The staging of his masterpiece, Guy Domville — whose hero has to choose between the woman he loves and his vocation as a Catholic priest — forms the kernel of Lodge's story and dominant theme.

The lead–-up to the first night is described in agonising detail. James is too nervous to attend the performance. He paces. He eats a sacramental meal, described in minute detail. Instead of watching his own play he opts foolishly to attend the latest Oscar Wilde hit, An Ideal Husband.

The tortured hours are his garden of Gethsemane, the meal his last supper. The ecstatic laughter and applause at the Wilde farce acts as a kind of epiphany, when he realises what the audience actually wants and how very far from it is his own strangled oeuvre. Guy Domville is serious, intellectual and ultimately bleak — qualities completely at odds with West End theatre tastes of the 1890s.

Unaware of just how badly his play has bombed, James arrives at the theatre in time to be invited on to the stage by the actor manager George Alexander. Only when he is greeted with boos and hisses does it become clear that the cries of 'author, author' are ironic. The audience, packed with his supporters and friends, is unable to stem the taunts from the gallery. And it includes everyone of note in London. Three of the reviewers present that evening are Arnold Bennett, George Bemard Shaw and the fledgling reporter H G Wells.

The moment of deep humiliation is his crucifixion. "What became more and more obvious, as the total picture became clearer, was that Alexander had betrayed him by inviting him to take a bow, as surely as Judas betrayed Jesus with a kiss."

In the weeks that follow James is forced to reconsider every aspect of his life. "He found himself engaged in what Roman Catholics called an examination of conscience, which a Monsignor of his acquaintance had once explained to him was part of the preparation for Confession."

The result is that he resolves to return to his true calling: the writing of fiction. The great novelist, in other words, is resurrected. There are explicit references to his followers — young men of letters usually — as his disciples, and to his temptations: diversions from serious endeavour in the service of art.

The gospel parallels are tiresome enough. But Lodge is not content with them. He is a worshipper not merely of his subject but of his metaphor — and he is compelled to conjoin them, despite James's well–documented agnosticism.

When Du Maurier declares his own atheism, James replies: "Like you, I'm a sceptic when it comes to doctrine. But I must admit to a kind of emotional attraction to the Roman Church — emotional and aesthetic. I adore Italian painting from Giotto and Botticelli to — oh, Tintoretto, Titian … those old masters humanise the biblical legends in a way I find immensely moving…And I rather envy the Romans their rituals and symbolism."

Clearly, this is Lodge rather than James, struggling to squeeze the facts into his preferred version. At this point he is honest enough to allow James to assure his friend that he would not consider converting: "Consciousness is my religion, human consciousness."

At the end of the novel, departing entirely from his pretence at fiction, he mounts an earnest reintepretation of James' essay 'Is There a Life After Death?' positing that the old man was a believer after all.

Such a clumsy intrusion into the semi–fictional world he has attempted to evoke highlights the faultline running through this ambitious work. Lodge's identification with James is so overwhelming that he has to idealise him as a saint and a believer. It accounts for the occasional lapses into infelicitous sentiment, tired phrasing and intrusive personal details that would have appalled the American. The ending, when Lodge addresses "Henry, wherever you are…" is just embarrassing.

There is plenty to savour in this entertaining dramatisation. But it is ultimately blighted by Lodge's inability to distance himself from his hero — and by his consequent attempts to emulate him. Lodge is no Henry James. His agenda is too clear; his sensibilities too blunt. And his sentences are too short.

Author, Author is available from Amazon (UK)