Polishing off his dad's books is not something Christopher Tolkien will make a hobbit of.

For The Children of Hurin, which his father JRR Tolkien abandoned in 1918, has taken him almost 30 years to complete.

In a move eagerly anticipated by millions of fans across the world, The Children of Hurin will be published worldwide on April 17 - 89 years after the Oxford author started the work.

The book, whose contents are being jealously guarded by publisher HarperCollins - is described as "an epic story of adventure, tragedy, fellowship and heroism".

It is likely to be a publishing sensation as it is illustrated by veteran Middle Earth artist Alan Lee, who won an Oscar for art direction on Peter Jackson's third film The Return of The King which was released in December 2003.

Mr Lee provided 25 pencil sketches and eight paintings for the first edition of the book.

The illustrator will be appearing for a signing session at Borders Bookshop in Magdalen Street, Oxford, on April 20, at 1pm.

Events manager Charlies Hayes said: "Alan Lee is very well respected as a Tolkien illustrator and this is a massive event for us."

Tolkien experts are already tipping The Children of Hurin - which features significant battle scenes and at least one major twist - for big budget Hollywood treatment. Box office takings from the 2001-2003 Lord of the Rings trilogy total £1.5bn to date.

Chris Crawshaw, chairman of the Tolkien Society, said: "It would probably make a very good movie, if anyone can secure the film rights. Tolkien saw his work as one long history of Middle Earth - from the beginning of Creation to the end of the Third Age. The Children of Hurin is an early chapter in that bigger story."

The author's son Christopher, using his late father's voluminous notes, has painstakingly completed the book, left unfinished by the author when he died in 1973.

The work has taken the best part of three decades, and will signify the first "new" Tolkien book since The Silmarillion was published posthumously in 1977.

David Bradley, editor of SFX magazine, said: "It will be interesting to see how it stands up today alongside all the Tolkien-alike literature we've become familiar with."

JRR Tolkien, an Oxford University professor, started The Children of Hurin after serving in the First World War. The story is set in the legendary Middle Earth of elves, hobbits and dwarves brought to life in The Lord of the Rings.

Christopher Tolkien, who lives in France, has spent decades organising, deciphering, drawing maps and editing his father's work.

He said earlier: "It seemed to me for a long time that there was a good case for presenting my father's long version of the legend of the children of Hurin as a independent work, between its own covers."