Robert Crawford is a masterly biographer who focused his microscope-like research eye on the details of T.S. Eliot’s early life in Young Eliot (2015). He traced the literary influences, Harvard education, religious background and Prufrock-like personal foibles that led to the poet’s pessimistic 1922 bombshell The Waste Land. It blew English poetry apart. And the dust has been settling ever since.

Crawford has gone much further with his new 600-page volume, revealing Eliot in his middle years and old age. Using love letters, which had been under lock and key for half a century, he lifts the mask the poet used to hide his inner torment. Stripped bare, Eliot’s core personality is referred to as plain “Tom”. The biographer has studied his poetic genius for decades. But he’s no Eliot fanboy.

He writes: “I try to present Tom Eliot’s life and work without undue moralising, letting readers reach their own conclusions.” His balance is scrupulous in this warts-and-all account. The poet’s embarrassing sophomoric locker-room verses have their place, as well as his anti-Semitic lines and utterances – plus the moment as a Faber & Faber editor, when he rejected Orwell’s Animal Farm to avoid upsetting Britain’s ally, Stalin.

Crawford begins his tale in 1922, the year when Tom’s hero, James Joyce, published Ulysses and Virginia Woolf was meditating on Mrs Dalloway. She and her husband, Leonard, published The Waste Land in England. Crawford includes quotes from the perceptive Virginia as she came to terms with Tom in a complex, platonic relationship. She found him paradoxical and said he had a “sphinx-like” smile. The young American poet Allen Tate also called him a sphinx.

Behind the smiling mask, there was a lot of angst in Tom’s soul. The young workaholic’s attitude to sex was troubled, and he wondered about forsaking his Unitarian faith in favour of Catholicism. Tom was torn between America and England, and thought of becoming a naturalised Englishman. He was a heavy smoker, a martyr to bad teeth, and a lover of gin. A truss kept his congenital hernia in place, but this didn’t stop him dancing on his nimble feet.

Eliot had studied literature, theology and philosophy in America, England and Europe, building an encyclopaedic store of knowledge and acquiring fluent French. He arrived in London just before the Great War, determined to make his name as a poet, and relentlessly networked the city’s literary avant-garde. Tom soon knew everyone who was anyone, and Crawford’s masterpiece is rich in entertaining anecdotes and colourful characters. He spent his wage-slave days in a basement at Lloyd’s Bank, dressed like a city gent, puffing fags as he researched German post-war payments to the Allies. In the evenings at home, he battered a typewriter late into the night, as editor of The Criterion literary magazine, funded by the irascible Lady Rothermere.

His wife of seven years lay alone in her separate bedroom. After a three-month courtship and an impulsive wedding to his petite dancing partner Vivien Haigh-Wood, Tom lost his virginity in 1915 at the age of 27. But he soon found himself serving a life sentence, tied to a chronic invalid. His own health was affected by anxiety and overwork. But Vivien was intermittently ill, with constantly changing symptoms that defeated one expensive specialist after another. She said, “You know I love Tom in a way that destroys us both.” Was she hooked on chloral hydrate? The suggestion remains unproven, says Crawford. But the treatments inflicted on the poor woman seem like sheer quackery to a 21st-century reader.

At times, the tale resembles a literary soapie. Vivien had a liaison with a cold-hearted seducer: the philosopher Bertrand Russell. Tom turned a blind eye and fell from grace with Nancy Cunard, whose daddy owned a fleet of ocean liners. But this left “a taste of ashes”, as he confessed in a secret letter to his one true love in America: Emily Hale. Crawford draws on a recently released trove of their love letters: testament to a passionate epistolary affair that went on in secret for decades, while the sphinx kept smiling.

Crawford wastes no time in discussing Eliot’s works. Rather, he delves deeply into how they took shape, formed by the poet’s background, studies, attitudes, and experiences. How he turned this rich mixture of sources into a polished poem makes for fascinating reading. The poems did not come to him easily. Each one was a struggle to produce. Fragments were assembled piecemeal over time in multiple drafts. Along the way, he was plagued by doubts. One notable exception was The Journey of the Magi, which materialised in a single session, fuelled by half a bottle of Booth’s gin.

Tom took up British citizenship and became an Anglo-Catholic, which left Virginia Woolf aghast. He confessed weekly. On a trip to Rome, he prostrated himself in St Peter’s. Crawford traces the career of a literary enfant terrible who was sliding rightward in politics to become a royalist London club man and a churchy pillar of the establishment. He left the bank and became a publisher with the firm later known as Faber & Faber. His poetic career led to Four Quartets, completed during the war years, when Tom was an air raid warden during the Blitz. He was still celibate and fended off the unrequited passion of his colleague, Mary Trevelyan, when she proposed marriage.

Post war, he collected gongs: a Nobel Prize, a British Order of Merit and a French Légion d’Honneur. In South Africa he met Stuart Cloete and Jan Smuts. In New York he was introduced to Einstein, Dirac and “people working on a thinking machine”. Prufrock had acquired a mask of gravitas and was no longer a cool cat but a square. He approved of Lady Chatterley’s Lover but thought Lolita “evil”. After Four Quartets, his poetic genius burned out – so says Crawford. But still the secret love letters flew back and forth, and the sphinx held nothing back from his transatlantic muse. Emily remained smitten – but every time she raised the question of matrimony, he said he was a married man. That excuse wore out in 1947, after Vivien died in an institution. Robert Crawford asks: “Did he want a mother, a muse, a lover, another wife or a blessed Virgin? Apparently, all of them.”

Valerie Fletcher had everything Tom wanted – except the Blessed Virgin part, judging by the explicit erotic verses she inspired, straddling his lap as “Tall Girl”. She had read The Journey of the Magi as a teenager and decided to marry the man who had written it. At 23, she managed to become his secretary. Seven years later he proposed by letter and bought her a huge emerald ring. Emily was informed and had a nervous breakdown. Meanwhile, despite all the indignities of old age – dentures, emphysema, walking sticks, tachycardia, and hernia operations – Valerie turned Tom’s final years into a non-stop honeymoon.

The mask was off. The celibate Prufrock had found fulfilment at last, and died in January 1965. His widow saw to it that a flood of Eliot papers were released after her death, and Robert Crawford has made good use of them. He has written a rich and rewarding biography.