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Now, for the first time since then, The Chaworth Roll will be seen in public again when it appears at an exhibition held by the manuscripts dealer Sam Fogg in London, who is offering it for sale at a six-figure sum.

At 21ft 4in (6.5m long) and 10in (25cm) wide, it consists of nine parchment membranes glued end to end.

It traces the royal succession from Egbert, "the first king of all England", who reigned from 829 to 839, through to Edward II (1307-1327). A continuation was then added in the early 15th century, updating it to the reign of Henry IV (1399-1413).

Only about 30 such genealogies produced between 1217 and 1327 are known to have survived. The Chaworth Roll is similar in style and content to three others, one in the Bodleian Library, Oxford and two in the Cambridge University Library. However, it is in much better condition than those and is said to be the finest of its type to appear on the market for more than 30 years.

Evidence suggests that it was commissioned by Sir Thomas Chaworth (1290-1347), a distant relative of the ruling Plantagenet family. He may have commissioned a roll for each of his four children - which would explain the versions that ended up in Oxford and Cambridge. The Chaworth Roll stayed in the family for six centuries, until it was acquired privately from the Chaworth-Musters in 1988 by a Norwegian who has now sold it to Mr Fogg.

The roll is mostly the work of a single artist, dubbed the Chaworth Master, whose drawings are similar to those of the Queen Mary Master, the illuminator of the Queen Mary Psalter in the British Library. His technique, however, links to an earlier English tradition of tinted drawings, a style that flourished in England before the Norman Conquest.

The portrait medallions of the kings also come with passages of text written in Anglo-Norman French summarising each reign with overviews of the various battles and events.

For instance, there is a brief account of the intrigue at the Anglo-Saxon court when Edward the Martyr (975-978) was murdered by his stepmother: "She gave him a treacherous kiss and a drink. As he was drinking, she wounded his body."

• The Chaworth Roll exhibition runs at Sam Fogg, 15d Clifford Street, London from March 3-24.