One of the most catastrophic episodes in modern library history was the Ashburnham House fire. On the night of 29 October 1731, a fire took hold below the room which held the famous Cotton collection, containing many of the most iconic historical and literary treasures from early times, among them Magna Carta, Beowulf and the Lindisfarne Gospels. Some of these items escaped the flames intact, others were singed or damaged by the water used to douse the fire, while many hundreds were burned significantly or completely destroyed. The fire-damaged survivors are held today at the British Library, but many of them remain extraordinarily difficult to handle or are too blackened to be read with the naked eye.

https://blogs.bl.uk/digitisedmanuscrip ... on-fragments-to-life.html

Some of these look just like Tolkien's illustrations for The Book of Mazarbul.