Book of legal and philosophical advice on king’s efforts to have his marriage to Catherine of Aragon annulled helped change the course of English history

A book which helped changed the course of English history, part of the evidence Henry VIII and his lawyers gathered in the 1530s to help win an annulment from Catherine of Aragon and ultimately to break with Rome, has turned up on the shelves of the magnificent library at Lanhydrock, a National Trust mansion in Cornwall.

The book, a summary of the theories of the medieval philosopher and theologian William of Ockham, has been newly identified by a US scholar and expert on the history of Henry’s library. The book was damaged but escaped destruction in a disastrous fire at the house in 1881, and crucially the fly-leaf survived. It still carries the number 282, written in black ink in the top right-hand corner, which Prof James Carley identified as corresponding with an inventory taken in 1542 of the most important of Henry’s books, five years before the king’s death.

Paul Holden, the house and collections manager at Lanhydrock, said: “It was an amazing moment. The old long gallery here is about the length of a football pitch, and the professor lapped it about six times when we found the book.”

There is nothing of Henry’s handwriting in the book, but Carley is certain it was consulted during the years when the king was desperately seeking a way, with the aid of Thomas Cromwell, of getting rid of his first wife Catherine, and marrying and conceiving a male heir with Anne Boleyn – the drama chronicled in Hilary Mantel’s Wolf Hall.

Henry’s agents were gathering evidence that could support the move, which may be how the collection of the views of the 14th century priest and philosopher, published in 1495, came to the royal library. Ockham wrote in Latin of the limits of the power of the pope, and the independence of the authority of monarchs. Several pages in the book have key passages marked by secretaries for Henry’s attention, including one crucial section with a heading which translates as: “When it is permitted to withdraw from obedience to the pope”.

In 1532 Henry would begin exactly that process of withdrawal from Rome. In 1533, despite its refusal to annul his first marriage, he married the almost certainly pregnant Anne Boleyn. Pope Clement VII declared that Catherine was still the rightful queen of England, and Henry responded with the Act of Supremacy, establishing himself as the head of the Church of England. The breach with Rome was complete.

Carley described the discovery as thrilling.

“The book is important not only for its provenance but for the notes entered in it by Henry VIII’s advisers and no doubt intended for him to see. They draw attention to precisely the sort of issues that were so relevant to the king’s policies in the years leading up to the break with Rome.”

In the 17th century, when many books were disposed of from the royal collection, it was acquired by a Cornish scholar and chaplain, the wonderfully named Hannibal Gamon, who left his signature on the title page. He in turn left the best of his books to his friend and patron John Robartes, first Earl of Radnor, at Lanhydrock. The book has sat on the shelves, rarely opened and its importance unrecognised, shelves ever since.

The library collection at Lanhydrock is famous, the finest among the National Trust’s properties, and far older than the present imposing granite house, which is almost entirely a Victorian replacement for the Jacobean building gutted by fire, when almost all the books were saved. Although the leather covers are original, the book’s spine was replaced after the fire which helped further disguise it.

Early this year Carley was among many scholars who come to use the collection, and Holden asked him to look at two volumes with the arms of Henry and Catherine of Aragon. Carley concluded they showed royal loyalty but not royal origins, but suggested it might be worth checking the collection for books from Henry’s library.

The two men started taking down every book marked in the Lanhydrock catalogue as older than 1542, and checking them against a copy of Henry’s inventory, and within an hour, when they reached Section C of the shelves, opened the book and saw the neat small number 282.

The book will now be displayed for the first time as a star object, rather than one more brown leather book among thousands, in an exhibition, Monarchy and the Book, when the house reopens to the public on 1 March.