A New South Wales library has had a book returned more than 150 years after it is believed to have been borrowed, with an estimated overdue fine of about $28,000.

The copy of Antiquities of Athens, published in 1858, was returned to Kiama Library last week after a local man discovered it hidden inside an old tea chest bricked into a sealed fireplace while renovating his home.

Library manager Michelle Hudson told AP it was the oldest overdue book the library had ever seen.

“We’ve never had anything that old come back to us,” she said.

Hudson said books occasionally reappear decades after they are borrowed, often when families are clearing out deceased estates, but nothing had come close to this.

The overdue fine was calculated based on the library’s original by-laws, printed inside the front of the book, which gave borrowers one month to return books before a three-pence-a-week overdue fine applied, according to Kiama Library’s Facebook page.

Kiama Library borrowing rules circa 1872.

Who last borrowed the book remains a mystery. “Unfortunately, we have a missing link. There’s nothing in the book that tells us who the last borrower was,” Hudson said.

The book, which has water damage from decades spent inside a chimney, was numbered 506 in the library’s original collection of fewer than 1000 books.

According to a Kiama Library Facebook post, it is believed the book was borrowed sometime between 1872 and 1890, when the library operated from the old Kiama School of Arts.

The Kiama School of Arts was home to the first Kiama Library.

The library’s borrowing rules from the 1870s offer a glimpse into a very different era.

Households could borrow up to three books if at least six family members were “known to be able to read”. Visitors arriving in a “state of intoxication” were not permitted to borrow, while borrowers had to return overdue books and pay any outstanding fines before they could borrow another.

Hudson suspects that last rule may have played a role in the mystery.

“Maybe that’s why they never returned it to us,” she said.

The book will now form part of the library’s local history collection and is no longer available for loan, the library said.

“We’re not going to allow it to go back out again. We don’t want to wait another 150 years for this book to be returned,” Hudson said.