A book that helped Henry VIII build his case against the pope and annul his first marriage has been discovered in a library at a country home.

National Trust undated handout photo of House and Collections Manager Paul Holden with the William of Oakham book that was once held in the Westminster Library of Henry VIII.

National Trust undated handout photo of House and Collections Manager Paul Holden with the William of Oakham book that was once held in the Westminster Library of Henry VIII.

The volume, dated 1495, is a summary of works by philosopher and theologian William of Ockham, a major figure in medieval intellectual and political thought.

Agents of Henry VIII scoured the country for texts such as Ockham’s, which questioned the authority of the pope and argued for the monarch’s independence.

Such evidence was used to annul the king’s marriage to his first wife, Catherine of Aragon, his brother’s widow, after she failed to produce a male heir, and ultimately break-up with Rome – a period of history documented in Hilary Mantel’s novels, produced for TV as Wolf Hall.

The book, which was found at the National Trust’s Lanhydrock in Cornwall, contains marginal notes and marks made by the king’s secretarial staff to draw his attention to relevant passages.

Highlighted passages include “when a synod is greater than a pope” and “when it is permitted to withdraw from obedience to the pope”.

National Trust undated handout photo of House and Collections Manager Paul Holden with the William of Oakham book that was once held in the Westminster Library of Henry VIII.

National Trust undated handout photo of House and Collections Manager Paul Holden with the William of Oakham book that was once held in the Westminster Library of Henry VIII.

Staff had been aware of the book in the library, which holds 2,500 volumes, but its direct connection to the royal marriage was not known until a visit from a Tudor historian.

Professor James Carley identified inventory number 282 inside the book, which corresponds to the inventory prepared for the king’s chief library at Westminster Palace in 1542.

Prof Carley, an expert on the libraries of Henry VIII, said: “It’s thrilling to discover that the book at Lanhydrock is from the royal library.

“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.”

The book is a summary of critical writings by William of Ockham, an English Franciscan friar and scholastic philosopher and theologian, who died in 1347.

Ockham is considered one of the major critical figures of medieval thought, with writings that challenged Pope John XXII’s condemnation of the Franciscan views on the poverty of Christ and his apostles.

His book was among writings, manuscripts and printed books that were brought to the king’s libraries and examined by staff to bolster his case for the dissolution of his marriage.

Wavy lines, signs and short marginal notes were inserted at pertinent places in the works.

The book at Lanhydrock does not contain any of Henry’s handwriting but has a number of the characteristic wavy lines accompanied by a # symbol used by the annotators.

Such material was used in the years leading up to the king’s marriage to Anne Boleyn in 1533, the Act of Supremacy in 1534 and the establishment of an independent English church.

At some point in the 17th century the book was acquired by Hannibal Gamon, a collector of many early scholarly books, whose signature is on the title page.

He later bequeathed his many such books to the Robartes family at Lanhydrock, a country house which was remodelled in the 1880s following a destructive fire.

Paul Holden, house and collections manager at Lanhydrock, said: “To have such an interesting book in the collection is fascinating in itself but to find out that it was once owned by Henry VIII, and played a part in a pivotal moment in British history, is very exciting.

“We’re really looking forward to seeing the reactions of visitors when they discover more about the story behind this remarkable volume.”

Lanhydrock’s library is among only a handful of pre-Civil War private libraries surviving in England.

Monarchy And The Book exhibition will open at Lanhydrock on March 1 and run until the end of November.

(Press Association)