IT has taken three decades, but the chronicles of one of the most important men in history will soon be published.

Essex University’s Gordon Chancellor made it his life’s mission to transcribe and publish 15 notebooks containing the thoughts and theories of Charles Darwin.

The notebooks were written by Darwin during a five-year voyage on the Beagle, and contained the basis for his theory of evolution.

It is hoped they will be published next month, to coincide with this year’s 150th anniversary of Darwin’s infamous publication, Origin of the Species.

Mr Chancellor, a business manager at the university, said: “I started work on it in the late Seventies after I read a book by Darwin’s granddaughter in which she mentioned the notebooks.

“I was convinced someone would already have done, or at least have started to, but no one had. So I started editing it in 1981, and had finished the first draft by 1985.

“But I got to a point where I realised it would be a lot easier to do it by computer. Laptops and things like that were starting to come out, and digitised text, which I knew would make it easier.”

Mr Chancellor, 55, who has worked in Colchester since last year, managing the business side of the university’s archives, needed help transcribing the text, written in a special metallic pencil which indented the page.

He got a helping hand from John Van Wyhe, of the University of Cambridge, and his researcher Kees Rookmaaker, who typed up all the notes.

Mr Van Wyhe’s expertise proved to be vital to the project, as he is editor of the website, and he became co-author of the book, which contains Darwin’s observations on rocks, fossils, plants and animals, maps, drawings, and even shopping lists and details of the people he encountered on the voyage.

Mr Chancellor said: “At times, it was very difficult to transcribe. His handwriting could be quite bad and his spelling was all over the place, too. In fact, his notebook pages looked a lot like a notebook does today, it had a mixture of longhand and shorthand for things, so I almost had to decode the notebooks in order to transcribe them.

“Sometimes he was on horseback, or something like that, so that could make his handwriting bad too.”

All of the notebooks, except one, are kept at Down House, in Kent, near to where Darwin lived.

“The most famous one, which covers when he was on the Galapagos Islands, is missing,” said Mr Chancellor, who has himself been to the Galapagos Islands twice.

“No one knows where it is, but microfilm of it made in 1969 still exists. It was from that, that I did my work. It is the most popular one, but it is actually one of the smaller notebooks.

“Most of the notebooks are about four or five thousand words long, but the one he took across the Andes was the most detailed piece of work he did. It went on for days and has about 22,000 words.”

According to Mr Chancellor, the notebooks show the thought process behind Darwin’s Origin of the Species. Mr Chancellor added: “Because he eventually published his theory of evolution, that makes the notebooks so precious.”

Darwin also wrote three diaries using the things he put down in his notebooks, a general one which he sent back to his family, one chronicling the zoology and a third about the geology.

“They are even harder to transcribe because, whereas Darwin only wrote in the notebooks once, he went over and over the diaries, and that makes it difficult to decipher.”

*The book, Charles Darwin’s Notebooks From the Voyage of the Beagle, is published by Cambridge University Press. It expected to be on shelves next month to coincide with the Darwin Bicentenary celebrations.