Owner Robert Webb said he had started looking for a new buyer last year in the run-up to his retirement and has now revealed the Harborough Road shop had been sold to a new buyer . . . but the new shop would not be selling books.
Mr Webb blamed cut-throat competition from the supermarkets which was making life increasingly difficult for independent bookshops.
He said when the last Harry Potter book was published in 2005, he was forced to buy copies from his local Asda and sell them on at the shop, because it was cheaper to do that than buy them from the publisher.
He said: "It's pathetic. The publishers sell them to supermarkets at one price and sell to us at double the price. Smaller shops haven't got a hope.
"It's just totally crazy.
"The publishers just don't want to know."
The final edition of the series is due to be published later this year, and Mr Webb said that even if his bookshop was still open then, he would not stock it.
He said: "I would just tell customers to go to the supermarket. It's a real shame and we would have liked to remain a bookshop but it's very difficult for individual bookshops now."
Mr Webb first opened the shop with his wife, Norma, in 1973 after working for seven years as a shoemaker. The shop opened in the midst of the three-day week and the couple had to cope without electricity for much of the time.
The store originally focused on Government publications, but now has a broad range of books on almost any subject, as well as a wide range of local books.
It also holds a monthly readers' circle in which bookworms meet to discuss selected publications.
The official closing date for the shop has not yet been confirmed by Mr Webb, but it is likely to be within the next two months.
alex.valk@northantsnews.co.uk