An ''outstanding'' collection of illuminated manuscripts previously owned by kings, bishops and the aristocracy is expected to fetch up to £16 million when it goes under the hammer.

The private collection, which Christie's described as the most valuable of its kind ever to be offered at auction, includes the personal prayerbooks of King Francois I of France and Elizabeth de Bohun, great-grandmother of King Henry V of England.

The Arcana Collection: Exceptional Illuminated Manuscripts And Incunabula, which has a total estimate of between £11 million and £16 million, will go on sale in July.