SPLIT WIDE OPEN: (From top) Sylvia Plath and Ted Hughes in happier times; Plath

In love, as in life, small actions can have catastrophic consequences. Assia Wevill once asked Fay Weldon to take care of Shura [Assia’s daughter] if anything should happen to her.

Did the fateful love affair between Assia Wevill and the late poet laureate, Ted Hughes, begin over a secretive kiss in the kitchen — witnessed by Hughes’s wife, Sylvia Plath — or was it fanned into life when Assia, insulted at being asked to peel the potatoes, flounced out into the vegetable garden and started to chat him up as he was picking beans? And does it matter anyway?

A new biography of the poet’s mistress A Lover of Unreason: The Life and Tragic Death of Assia Wevill by Yehuda Koren and Eilat Negev favours the kitchen sink version, as recounted by Assia’s third husband, David Wevill.

But the novelist Fay Weldon says it all started with a row over the potatoes. Cross at being asked to perform such a menial task by Sylvia, Assia — a house guest of Plath and Hughes — went out into the garden in a fit of pique to try her charms on Ted.

The interesting thing, in view of bigger controversies swirling round the book, is that Assia was the source of both accounts — one to her husband, one to her friend and colleague Weldon.

There is little doubt that Plath committed suicide at least in part because of her husband’s affair with Assia. Six years later, Assia also took her own life.

Shura, her four-year-old daughter by Hughes, was found dead at her side in the gas-filled room. Hughes had to live with the triple tragedy until his own death in 1998.

“You might say if Sylvia had not asked Assia to peel the potatoes, it might never have happened,” says Weldon. “She was very annoyed and got her revenge but it turned into something serious.”

The biography — serialised recently in The Daily Telegraph — has reopened this apocalyptic tale of passion and death provoking fresh and heated argument about the role of Wevill, the other woman, in the fate of Hughes and Plath.

Arguments have raged around dinner tables: was the poet a monstrous cad who drove two women to their deaths; was Assia a self-centred hussy; was the killing of her daughter an act of revenge against her lover?

The two versions of what ignited the affair are symbolic of other conflicts thrown up by one of literature’s most complex love triangles.

Elizabeth Sigmund, who became a friend of Plath and Hughes when they moved to Court Green, a Devon farmhouse, and who also knew the exotic Assia, objects strongly to the authors’ claim that Assia “was not an initiator in matters of the heart, but a responder”.

“Assia loved to provoke and to initiate,” says Sigmund, now 78. “She was interested in what power she had over people. She was determined to have an affair with Ted. Assia was a very confused woman.”

One night, after Sylvia had intercepted a phone call from Assia and confronted Ted, she fled to the Sigmunds for refuge.

“She was in a terrible state. She said: ‘He lied to me and he’s become a little man.’ Sylvia idolised him and promoted his work but he had become this shifty person. It made her despise him. Sylvia was very clear-sighted, an honest and sincere person. Assia was none of those things.”

Sigmund illustrates Assia’s manipulativeness with an incident that happened after Sylvia’s suicide. Ted took Assia to Court Green, and Sigmund was asked to show her round.

“When we got to Sylvia’s room, which was padlocked, she said to me: ‘Don’t you feel a traitor?’ What a question to ask me, knowing I had been Sylvia’s great friend! It wasn’t mischief; it was nastiness. I rushed downstairs in tears. Ted was tying up a carpet and weeping. I had never seen him weep before.”

Shortly after Sylvia’s suicide, Sigmund visited Hughes in London. “He looked absolutely distraught,” she recalls.

“He handed me a copy of The Bell Jar [Plath’s autobiographical novel] and said: ‘It doesn’t fall to many men to murder a genius.’ When I remonstrated with him, he said: ‘I hear the wolves howling at night.’ I could see the man was in pieces.

“Though he didn’t behave well with Sylvia, Ted was not the villain he has been made out to be. After Sylvia’s death, he went from one affair to another, hoping he could assuage his guilt and misery.”

Sigmund does not believe, as the book suggests, that Assia killed herself because she found out that Ted was being unfaithful.

“Even I knew he was having affairs with at least two other women. I think she killed herself because she realised that he would never marry her... that she and Shura would always be on the outside.”

Weldon, who worked as an advertising copywriter with Assia in London in the Sixties, also has strong views about the protagonists. She points to the infamous list discovered by Assia’s biographers Koren and Negev.

This reveals that the poet typed out two pages of instructions for his mistress; he ordered her to be out of bed by 8 am, to dress straight away and not to nap in the afternoon.

She was to teach German to Frieda and Nicholas, his children by Plath, for at least an hour a day and each week introduce “a recipe we have never had before”.

The discovery of this list, Weldon feels, makes Hughes appear to be a tyrant. “At the time,” she says, “this was how men behaved, especially if they were talented. Women were the normal sacrifice to art. In those days, men had art and women had babies. As a man, it was almost your duty to sap the vitality and female energy of those around you. Assia was serving a great artist.”

In Weldon’s view, the list is merely a “work schedule — something Ted banged out on a piece of paper to help [Assia]. It would have been very good advice. She was unused to children and baffled by the requirements of the job. Assia wasn’t lazy.

“She kept beautiful, pretty houses... with spotless tablecloths and polished glasses, but in her heart she wanted a maid. She was used to something better than Court Green, a damp house with no central heating.”

She has not spoken about Assia before because, she says, “I didn’t wish to take sides. It was serious and it ended in death and I didn’t want to engage with it on a gossipy level. You feel sympathy for them all: they all had their flaws. My view is you don’t condemn any of them.”

She says Assia once asked her if she would look after Shura if anything happened to her. “I didn’t see anything potentially suicidal about it. I took it to mean if she should be run over by a bus. But in retrospect, one might have wondered... She was a responsive, funny person with conversation and a sparkly interest in the world,” she adds. “Only when she became haunted by Sylvia did she become heavy and sad. That side of her doesn’t come through [in the book] — any more than Ted’s natural niceness and charm come through.”

But at least, says Weldon, the new biography means Assia at last has a voice after years of being a footnote in literary history.

“She is now an equal partner in what went on. I am pleased she’s being thought about. Now let’s leave them in their graves and pray for their souls — and the little girl.”