Jaguar in cage, thought-fox on page, hawk in rain, pike in pond: it was Ted Hughes who got me hooked on poetry when I was a teenager. I shall never forget the experience of hearing him read "Crow" at a little gallery in Cambridge when I was an undergraduate. Later, I felt that his career had gone into a midlife dip and I was exasperated by his huge book on Shakespeare, but I delighted in his return to form with Tales from Ovid. Sharing his passions for Wordsworth and Coleridge, for conservation and ecology, for the classics and the theatre, he was the obvious choice for my next literary biography after I had done with two of his favourite poets, Shakespeare and John Clare.
I knew that before he died in 1998 he had sold a huge archive of his manuscripts to Emory University in Atlanta. Elaine Feinstein made use of it in her 2001 biography – the only one to date. But the material was not even fully catalogued at that time: there was far more to discover. Then in 2007 his selected letters appeared, revealing him as perhaps the greatest English literary correspondent since John Keats, as remarkable a prose writer as a poet. And in 2010 a second archive was opened to researchers: the British Library had paid £500,000 for the materials kept back from the Emory sale.
The publication of the letters and the sale of the second archive by the poet's widow Carol suggested that she might be relaxing the position made clear by Hughes's publisher, Faber, soon after his death: that there would never be an "authorised biography" of this most controversial poet. So I made some inquiries and, to my surprise and delight, the estate – which is controlled exclusively by Carol Hughes – approved of my plan for what I called "a literary life". My editor at Faber introduced me to Carol. They walked me through the streets of Bloomsbury to a restaurant in, of all places, Rugby Street – where Ted first made love to Sylvia Plath. I took this to be my symbolic anointing, though we kept the form of words that the book was not to be called a biography and that the estate was providing "full co-operation" rather than "authorisation". After that lunch, I wrote in my notebook that Carol had expressed herself "totally happy with my idea of using the life to illuminate the work". She told me that she wanted such books to be published in order to keep Ted's work alive and interpret it for new generations of readers. She said that the last thing she wanted was to be perceived as another Valerie Eliot – famously, TS Eliot's widow slowed down the publication of his letters to a snail's pace and banned all quotation from his work in biographies. This diminished Eliot's reputation: forcibly starve a poem of the oxygen of critical attention and it will die. By contrast, Carol even provided me with photocopies of letters from the Emory archive, to reduce the amount of time I had to spend in America.
So I spent four years immersing myself in every word Ted Hughes published – more than 100 books – and in the books in his library, the memoirs of his friends, the work of the younger poets he supported, and above all the archives. I have had incredible help from his family and friends and from librarians and archivists around the world (materials are to be found even in such unlikely places as the Australian Defence Force Academy). Loyal supporters such as Seamus Heaney and the American writer Ben Sonnenberg gave me wonderful interviews before their untimely death. Olwyn Hughes, Ted's sister and for years his literary agent and "gatekeeper", has been a font of information and opinion. Sometimes we quarrel – she and I have very different views of Sylvia Plath – but always she wants the best for Ted's work.
Astonishingly, Olwyn didn't even know that Ted kept a diary. It wasn't organised and systematic like Plath's, but piecing together thousands of pages of memorandum books, loose leaves and pocket notebooks in the British Library, it became clear that this was an almost complete record of his inner life, amounting to nearly a quarter of a million words. Fascinatingly, the journal and the Birthday Letters project proceeded in tandem through the years. Sometimes you can't even be sure whether a piece of writing is a journal entry or the draft of a poem about Hughes's life with Plath and its legacy.
The sheer size of the archive and the complex task of stitching experience, memory and poetry together into a coherent narrative meant that, just before Christmas, I had to ask Faber for an extra year in which to finish. They were relaxed: many a scholarly biographer has asked for much longer extensions than that. I was on the brink of sending them about half the typescript in draft form when they received a letter saying that the estate of Ted Hughes was withdrawing its co-operation from my book. No reason was given.
Faber were placed in an impossible position. As Ted Hughes's publisher, they couldn't possibly proceed with a book that did not have the support of his copyright holder. They behaved impeccably: sadly but amicably, we parted company.
By a curious coincidence, I was in the position of knowing a lot about copyright law in relation to literary works. That was because of the strange case of John Clare's copyright, whereby a living editor claimed the copyright of a poet who had died in a madhouse a century and a half ago. With help from a very experienced intellectual property lawyer, I got round that problem and managed to publish my biography of Clare without ending up in court. So I turned to my learned friends once again.
The paradox is that although the documents were bought by the British Library with taxpayers' money, and can be seen by anyone, the right to quote at length from them rests with the estate. However, copyright only exists in the exact words of an author, not their ideas. So it was that Peter Ackroyd, writing his biography of TS Eliot, could use paraphrase to get round the Widow's Restrictions. In addition, the Copyright Act does not require a scholar to seek a licence when quoting small amounts of literary works for the purposes of research, of "criticism or review," of news reporting, or indeed in "the public interest". In all these cases, a rule of "fair dealing" applies. It is sometimes said that there is a "10% rule" or a particular restriction on word count, but in fact the concept of "fair dealing" is wonderfully vague, determined only by case law when infringement actions are brought to court.
The irony of the estate's action is that, though informed by biographical background, the main emphasis in the Faber book was the development of the poetic voice, with pages and pages of detailed analysis of the multiple drafts of the poems. But with quotation now limited to fair dealing most of this will have to go, and the new version will be much more biographical. I am disappointed at losing so much of Hughes's wonderful written voice, but it is actually proving good writerly discipline to weave his thoughts in with my own words and not to fall back on big blocks of quotation. And I no longer have to worry about that rather artificial distinction between "biography" and "literary life".
• Jonathan Bate's Ted Hughes: A Biography will be published by William Collins in autumn 2015.
