They hailed Birthday Letters, the sequence of 88 poems to be published next week by Faber & Faber, as one of the great literary discoveries of our times. The poems tell Hughes's side of the story of the relationship he had with Plath, the extraordinarily talented but tormented American poet, who committed suicide in 1963.
Until now we have had to interpret their life together through the poems, letters and diaries of Plath. Hughes has often been vilified by feminist critics for his treatment of her.
Although Hughes has written occasionally about Plath in the past, and was the shadowy figure behind Anne Stevenson's controversial "authorised" biography, Bitter Fame (1989), the existence of a full poetic sequence describing the relationship is an unexpected end to his long silence.
"Some of the poems have been printed in the New Yorker over the years," said A Alvarez, a friend of both Plath and Hughes in their early days as young poets in London, "but I had no idea he had a whole book of them."
Hughes's New Selected Poems 1957-1994, published in 1995, ended with a series of "Uncollected" works clearly addressed to Plath, among them "You Hated Spain" (the scene of their honeymoon) which explains: "Bosch/ Held out a spidery hand and you took it/Timidly, a bobby-sox American." "The God" begins "You were like a religious fanatic/ Without a god - unable to pray./ You wanted to be a writer... 'God is speaking through me,' you told me./'Don't say that,' I cried, 'Don't say that. That is horribly unlucky!'"
Speaking to himself, now, in "The Error", Hughes muses: "Maybe they wouldn't stone you/If you became a nun/And selflessly incinerated yourself/In the shrine of her death."
Now, added to these are poems revealing, for example, the couple's first sexual encounter: "You were slim and lithe and smooth as a fish./You were a new world. My new world./So this is America, I marvelled./ Beautiful, beautiful, America!"
The new sequence tells the whole story, from the night they met in Cambridge to the poems of mourning for her death.
Twenty five years in the making, the sequence was begun sometime in the late Sixties, and completed in the mid-Nineties. At times the poems echo Plath's own short, staccato lines and cadences: "The story of your God/Who embraced you/And your mummy and your daddy/ Your Aztec Black Forest/God of the euphemism Grief".
Looser, almost adolescent in fervour and more intimate than his famous works, they will come as a surprise to anyone who still associates Hughes with blunt, bloody animal poems.
On a more biographical level, the passion and pain evident in the work should put paid to the simplistic "St Sylvia and evil Ted" myth which presents a fragile wife dominated and then deserted by an unfeeling husband.
Fuelling the myth were lurid tales such as the one suggesting Hughes had held a wild party in the flat where Plath gassed herself; a party involving, of all things, celebratory playing of bongo drums.
"I certainly never got the impression that he was anything other than totally devastated by what Sylvia had done," said Mr Alvarez.
Of Hughes's long, patient silence, he remarks: "There is a new media morality now. Whereas in the past these things weren't spoken of, now you're considered a bit suspect if you don't talk about them publicly." Why did he think Hughes has chosen to break his silence now? "You only have to look at the calendar. Ted is coming up to 70. He can't keep it to himself for much longer."