The British Library has admitted an historic diary was damaged while in its care, but refused to confirm reports the book had been left in a car boot.
The Library said its report into the damage was confidential
Owner Peter J Tyldesley handed over the manuscript in 1994, believing it would be safer in the Library than his home.
The solicitor told The Times he "wanted to weep" when he discovered oily stains on the pages seven months ago.
He claimed the book had been removed from the library. A Library spokeswoman said there had been an investigation.
"The diary was damaged. It was discovered earlier this year," she said. "We are working with the owner to restore the damage."
She confirmed there had been an internal investigation, but said the details would remain "confidential".
A member of staff had since left the Library, the spokeswoman added.
However, she refused to confirm allegations in the Times that the diary had been stored in the boot of a car.
The 18th century manuscript was written by Mr Tyldesley's ancestor, Thomas Tyldesley, a prominent Jacobite who used the diary to record his preparations for the 1715 rebellion.
Among the entries, the diarist noted the celebrations he attended after learning of the death of Queen Anne - an event which was expected to trigger the uprising.
"Wee spent 2s (shillings) each," he wrote, "beeing invitted to a pige feast" .
In May this year, the British Library issued a statement describing the damage to the diary.
The original binding had been removed and replaced, it said, although this action "was authorised neither by Mr Tyldesley nor the Library".
"The staining appears to have occurred when the diary was not in its archive box. In addition to the staining the diary has at some stage unfortunately been damaged by damp, mould and mildew."
"The diary was in good condition in 2002," the statement continued. "The damage occurred sometime thereafter."
Mr Tyldesley has criticised the Library for not making public its report into how the book came to be damaged.
"There certainly seems to have been a complete absence of effective management controls," he told The Times.
"Obviously the wider concern must be whether this was a one-off incident."