For the first time in its history, the National Trust is compiling a catalogue of the 400,000 books in its possession.
Of all its libraries, the one at Blickling Hall is the biggest and most important of them all.
It estimates the Long Gallery Library holds between 12,500 and 14,000 books and there's only one man to catalogue them all.
Librarian John Gandy has spent the past four years painstakingly going through the collection and is only about a third of the way through.
He said: 'When I started I estimated it would take ten years.
'Now its gone up and I think it's going to be closer to 12.'
The ambitious project aims to compile a complete list of books on an online database.
This means John has to input as many details as he can find, which can sometimes involve detective work.
He said: 'We've got some books written in Arabic and on the cover it says in Latin that they are the end of the Koran.
'We had some Arabic speakers come in to look and they said it's not the Koran but they don't know what it is.'
The collection at Blickling Hall covers theology, law, natural sciences and more, but the illustrated books catch John's eye the most.
He said: 'We've got a stunning collection of atlases from the 16th and 17th centuries.
'They're stunning works of art and I could quite happily just sit all day and leaf through them'
While a lot of the books are important academic works, there is some light reading among the shelves.
John said: 'We've got about a thousand novels, including first editions of Jane Austen's Emma and Sense and Sensibility.'
The task might seem daunting, but John is focussed on the end result - a complete record of the hall's library.
He said: 'The ultimate aim is to allow access to the books.
'In the past, the National Trust has had inquiries from historians and researchers about books and the answer has always been 'we don't know.'
'When the catalogue is completed we can arrange for people to come and see the books.'
To see the National Trust's collection so far, visit copac.ac.uk.
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