A SEARCH to establish the whereabouts of the remaining 13th-century manuscripts of Magna Carta has confirmed that almost a quarter of them are in the Bodleian Library, Oxford.

The survey was conducted in advance of Sotheby's sale of a rare copy of Magna Carta, owned by the Perot Foundation, which is expected to fetch more than £20m when it goes under the hammer.

The Magna Carta is considered one of the most important legal documents in the history of democracy, enshrining civil rights in English law.

It was agreed by King John at Runnymede in 1215 and was reissued five times during the 13th century by England's rulers.

There are 17 surviving 13th century charters, of which four are in the Bodleian.

Of the four surviving manuscripts from the 1217 issue, the Bodleian holds three.

Bodley's Librarian, Sarah Thomas, said the three charters were a unique historical collection.

Each charter originally bore the seals of the guardians of the boy King Henry III, William Marshal and Guala, the Papal Legate to England.

She said all four Oxford charters would be displayed together in public for the first time in 800 years in the Divinity School at the Bodleian Library on Tuesday, December 11 the day of the Sotheby's auction in New York City.

Two of the charters were sent to Oxfordshire by the Exchequer and have remained in the county for almost 800 years.

The Bodleian also holds a 1225 issue, which would once have held the Great Seal of Henry III.

The seventeen original manuscripts of the Magna Carta are official documents from the Royal Chancery bearing the rulers seal.

Those not held at Oxford are distributed between nine other locations in Britain, Australia and the United States.

The Magna Carta came into being as the result of a dispute between King John and English barons, guaranteeing basic freedoms and property rights to those considered "free men".