0415 GMT December 09, 2021
St. John Fisher Catholic High School in Peterborough, loaned the hardback Manners Make A Difference in 1989, BBC reported.
Last week it arrived in the post, with an unsigned note: "Sorry! Just 32 years overdue! Call it Catholic guilt."
The fine — which will be waived — would have been £832, the school joked on Twitter.
Jo Sennett, a librarian at the school, said: "The fact that someone has sent it back, and that it's about manners, is lovely.
"We would love to find out who sent it.
"The school community is a family, and they've clearly remembered that and taken that into adulthood."
She said it felt like the book had come "full circle" as the package was initially opened by a member of staff who was a St. John Fisher pupil in 1989.
The US tome, distributed by the John C Winston Company, includes some rather "archaic wording", added Sennett, the school's special educational needs coordinator, who also works in the library.
"It can only have been used as means to reflecting how society has changed, and possibly in A-level sociology," she said.
The book looks at manners in different areas of life, including at school, at the table, while playing games, letter writing and traveling.