Edith Sitwell: Avant Garde Poet, English Genius, By Richard Greene

Dame Edith Sitwell (1887-1964), like her younger brothers Osbert and Sacheverell, will certainly always be a footnote in English literary history, though it may be for what her supporters would consider all the wrong reasons: scandal, not literary skill. Victoria Glendinning's able life, A Unicorn among Lions, made the case 30 years ago for Sitwell as author, poet - even feminist trailblazer. Now Richard Greene, a Canadian academic, has furnished us with a new account, drawing on previously unseen letters, and written in light of recent biographies of her siblings.

The problem is that Greene's primary aim – to resurrect her poetry as among the high achievements of modernism – simply doesn't come off. Sitwell's later verse never completely fell off. But it succumbed to a sort of spiritual "set-piece-ism", both eccentric and banal. Greene selects for particular appreciation a post-Hiroshima poem entitled "The Shadow of Cain" – which is fine, until you read it: "We did not heed the Cloud in the Heavens shaped like the hand/ Of Man. But there came a roar as if the Sun and Earth had come together".

In her day, Sitwell was – even when favoured – essentially a curiosity: with her perverse, gothic-maiden look, quintessential vulnerability, cultivated hauteur and predilection for the endless pursuit of men. These fell into three kinds: hostile critics (always numerous); deceitful, manipulative family members (all of them) and unavailable, yet attractive homosexuals (Siegfried Sassoon, Pavel Tchelitchew).

The unconvinced lampooned her. All three Sitwells featured in Wyndham Lewis's The Apes of God (1930); certain of their traits – particularly Osbert's – crept into DH Lawrence's Lady Chatterley's Lover (1928). But it was FR Leavis's stony 1932 verdict that did for Edith and her brothers: "the Sitwells belong to the history of publicity rather than of poetry". Wicked as it is to note, the Wikipedia entry for "Publicity and Controversy" under her name dwarves its discussion of her verse. At the time, it may not have seemed eccentric of Yeats to accommodate Sitwell across 18 pages of his Oxford Book of Modern Verse (1936). Today it does.

In their tendency to defend one another's writings, the Sitwells may have drawn not just on familial loyalty, but genuine artistic like-mindedness. Sometimes, though, perception is all. When Osbert reached around the curtain shielding him and his megaphone-bearing sister during their recitation of Façade - a poetry suite Edith had worked on with William Walton – he meant to explain the dense verse to the masses. Instead he provoked Noel Coward into one of his sharpest spoofs: the Sitwells as "the Swiss Family Whittlebot" in London Calling (1923). For 40 years Edith "very simply hated" Coward for his "Hernia Whittlebot".

She made misjudgments, resorting readily to libel proceedings against critics. Even Sitwell's modest success in silencing her opponents and winning damages struck others as presumptuous and inappropriate in a land which valued free speech, and found itself at war defending it.

All three Sitwells had a fatal facility for writing. Sachie could pen a second-rate travel book every few weeks, skipping across continents and cultures. Osbert's portentous, five-volume autobiography Left Hand, Right Hand now strikes the reader as almost as long as the century it traverses. Still, Edith had one excuse her brothers lacked: the near destitution in which she was abandoned - first by father Sir George; later by the connivance of Osbert, his heir. She was effectively compelled to write ephemeral books to stay afloat. Few can fail to be moved by her anger on learning how little she had been left on Sir George's death: "He has tried to murder my poetry."

She was capable of exceptional kindness. Despite her poverty, she accommodated her former governess in her lodgings in unfashionable Bayswater for decades. Sitwell put on modest literary salons, only to find her generosity ridiculed by those for whom money was no object. Her record on anti-Semitism proves impeccable, in stark contrast, say, to Virginia Woolf. She was capable of independent-minded judgments, effectively ushering Dylan Thomas, Denton Welch and American novelist James Purdy into print.

Greene's account is exhaustive, though somewhat marred by those biographer's curses, hindsight and generalisation. Sometimes expression itself feels awkward, as in the unfortunately comical claim that "Joseph Goebbels was the right opponent for Edith Sitwell". Still, this life is sincere enough. If Sitwell's life and career were hardly emblematic of the times in which she lived, but progressively marooned by them, they were deeply suggestive of their age. Façade I still think fun. If that is to be Sitwell's footnote on 20th-century culture, she might have done much worse.

Richard Canning's edition of Ronald Firbank's 'Vainglory' is forthcoming from Penguin Classics