In 1939, Graham Greene wrote to his brother Hugh: “A new shade for knickers and night-dresses has been named Brighton Rock by Peter Jones,” adding: “Is this fame?” Greene was then 35. Brighton Rock (1938) was his first critically acclaimed religious novel. It describes a betrayal of loyalties in gangland Britain and remains a disquieting parable of conscience. (Greene had converted to Catholicism 13 years earlier.) By the time of his death in 1991, with more than 30 novels to his name, Greene was a prolific chronicler of human faith and wretchedness.

A writer of his stature would need an extremely good biographer and, at first, it looked as though Greene had found him in Norman Sherry, a Joseph Conrad expert based in Texas. Sherry set to work in 1976, digging and hustling. His first, 700-page volume up to 1939 scrutinised Greene’s every depression, adulterous affair and alcoholic spree. “Why does Sherry waste so much time writing about me?” Greene grumbled. Sherry had gone temporarily blind during his researches in Africa and endured gangrene in Panama. (“I do hope I am not going to be the death of him,” Greene commented darkly in a letter of 1978.)

By the time Sherry’s third and final volume appeared in 2004, it was clear how ill-served Greene had been. Running to a combined total of 2,500 pages, Sherry’s life of Graham Greene combined hagiography with locker-room snooping. Richard Greene (no relation) is another who finds Sherry indecorous. His impeccably edited Graham Greene is intended in part as a riposte to the trifling Sherry and other “dirty linen” biographers who have sought to expose a darker shade of Greene and, in consequence, lost sight of the writer and his books.

Like many of his generation, Greene was punctilious in answering his letters: in old age he received an average of 180 a month. Richard Greene, a Canadian poet and academic, has chosen to publish the gems. The result is a triumph of judgment and judicious selection that offers a vivid new picture of Greene the man: his pleasures, foibles and, above all, generosity. Attentive to friends in need, he gave away much of what he earned. Muriel Spark was one of many writers who benefited financially from him. (“Don’t make your books any shorter, please,” Greene wrote to her in 1974, “or you’ll disappear like Beckett.”) Mervyn Peake, stricken by Parkinson’s disease in the late 1950s, was another. Greene was especially pained by the penury of the wives of Soviet dissidents; he made sure his Russian royalties went to them. His correspondence with the south Indian novelist RK Narayan, is a high point. Concerned that Narayan’s real name (Narayan Swami) would hinder sales in Britain, Greene advised him to use a pen name (“I saw an excellent novel by a German completely fail because of the supposed difficulty of his name: Erik von Kuhnelt-leddihn!”), and moreover saw to his financial security.

Notably, the letters reflect personal anxieties of betrayal and cold-war double-dealing. Greene’s father had been the head-master of a public school outside London, and, as a boy, young Graham learnt to realign his loyalties as he left the family quarters to go to class. Greene had known Kim Philby during the war when he worked for him in British Intelligence in west Africa, and they stayed in touch long after Philby had been exposed as a Russian agent in 1963. The Greene-Philby correspondence, as reproduced here, is rather anodyne, as talk is of vodka and meals consumed in Moscow during the 1980s. Whether Greene suspected “his dear Kim” of being a Soviet infiltrator before his unmasking may never be known, according to the editor.

In Catholicism, Greene had found a sense of melodrama – an atmosphere of good and evil – that was useful to him as a novelist. His letters in the 1920s to his fiancée Vivienne Dayrell-Browning, a committed Catholic, suggest a defection to Rome on intellectual impulse, as well as a bid to please his future wife. (Vivienne was his “Puss Willow”, while Graham her “Wuffle”.) By 1947, however, Greene was involved with Catherine Walston, a married American. His letters to “Cafryn”, alternately tender and steamy, were sometimes fuelled by alcohol. “You’re my human Africa,” Greene tipsily wrote to her in 1949 from Dakar. “I love your dark bush as I love the bush here.” According to an earlier biographer (not Sherry, this time) they enjoyed the frisson of adulterous copulation behind church altars. Certainly, the letters are erotic (“I want to spill myself out into you”), and charged with yearning (“I am thirsty for orange juice at 3 in the morning. I want to see you in your pyjama top . . .”). However, no mention is made of altars.

Above all, the letters confirm Greene’s considerable wit, capacity for terse put-downs and fascination for what remained outside his class and culture – whether it was blue films in preCastro Havana or marijuana in Jamaica. His judgments of lesser writers could be caustic. Stephen Spender has “too much human kindness” (rarely a good thing in Greene); Salman Rushdie displays “shocking bad taste” in The Satanic Verses. Greene was intrigued by sexual mavericks: while Truman Capote is judged to be a “most queer fellow not only in the technical sense”, the louche Italophile Norman Douglas was a good friend. Greene’s venomous 1988 spat with Anthony Burgess is given a good show: their friendship ended spectacularly after Burgess referred in the French press to a Greene anecdote involving “an aggrieved husband shouting through [Greene’s] window”. Greene’s response, addressed to “Dear Burgess” was curt: “You are either a liar or unbalanced and should see a doctor.” Among Catholic writers, only Evelyn Waugh won Greene’s unstinting admiration and love; his death in 1966 devastated him. “What I loved most in him,” Greene wrote to Waugh’s widow Laura, “was that rare quality that he would say only the kind things behind one’s back.” (Greene was wary of lavish compliments.)

For much of his life, the man Waugh schoolboyishly nicknamed “Grisjambon Vert” was prone to disabling bouts of melancholy. The thrill of travel on the dangerous edge – Papa Doc’s Haiti, Indochina – was perhaps a way out of depression, or simply a means to escape boredom. Although “profoundly antagonistic” to domestic life, Greene remained fond of his two children by Vivienne and kept in touch with them on his travels. (“All love from your wandering but loving Daddy,” he wrote to his daughter Caroline in 1959 from the Belgian Congo.) A wonderfully compelling record, Graham Greene: A Life in Letters comes as near as anything to the way Greene talked with friends and family. Now, perhaps for the first time, he emerges whole from the shadows of his biographers, as distinctive and memorable as any of his fictional creations.

GRAHAM GREENE: A Life in Letters edited by Richard Greene
Little, Brown £20 pp446
Buy the book here at the offer price of £18 (inc p&p)

Times Recommends

• 10 things you should avoid in hospital (unless there really is no option)
• Exclusive: Philip Pullman's essential reading list
• The White War by Mark Thompson