A final adventure for Paddington Bear, in which the marmalade-loving magnet for trouble visits St Paul’s Cathedral, will be published in June 2018, a year after the death of his creator, Michael Bond, at the age of 91.

“He was working on it very shortly before he died,” said Bond’s daughter, Karen Jankel. “It hadn’t been illustrated, but it was there in manuscript form, and it’s lovely … He kept that magic touch right until the end. He always had to be writing, it was always his way, right through his life.”

With illustrations from RW Alley, who has illustrated Bond’s Paddington Bear books since 1997, the publication of Paddington at St Paul’s will mark the 60th anniversary of the first book about the character, A Bear Called Paddington. In his latest exploit, the irrepressible bear sets off for the cathedral, where he is mistaken for a choirboy.

According to Jankel, the picture book was inspired by a ceremony there to celebrate the Queen’s 90th birthday, at which David Attenborough read Bond’s Reflections on the Passing of the Years [pdf].

“That’s how the idea got started,” said Jankel. “I’d never give away too much, but Paddington goes on an outing with his friend Mr Gruber, as he is wont to do.”

Ann-Janine Murtagh, executive publisher at HarperCollins Children’s Books, called the final Paddington book “Michael’s parting gift to all his fans … brimming with curiosity, charm and affectionate exuberance”.

Jankel said that she had been “surrounded by Paddington all my life” – she was born on 13 August 1958 and the first Paddington book was published on 13 October that year. “He was like a member of the family. He still is, even though my father isn’t here.”

Bond, who began writing in 1945 while in the army, and sold his first short story for seven guineas, will be celebrated with a memorial service at St Paul’s on 14 November. “Our family feel immensely proud that we will be honouring his life [in this way] and the fact that this is the setting for his final story makes it very special indeed,” said Jankel. The service will feature tributes from family and friends, as well as from the actors Hugh Bonneville, Madeleine Harris and Samuel Joslin from the cast of the film Paddington 2, which is out on 10 November.

“It’s wonderful,” said Jankel of the film. “Very sadly my father never got to see it. They’ve captured the spirit of Paddington so beautifully. My father was as nervous as me before the first one. We all were. It’s like asking somebody to bring up a child for you. But when he finally saw it, he was delighted.”

Bond was first inspired to write about Paddington when he saw a small toy bear on a shelf in a London shop on Christmas Eve, 1956. Feeling sorry for it, he bought it as a present for his wife. Living near Paddington station, he’d often thought that Paddington would be a good name for a character, and one day, it gave him the spark of an idea.

“When I wrote those few words, I had no idea quite what a change they would eventually make to my life. It was really a case of putting something down on paper to get my brain working that morning,” Bond said.

Jankel added: “He didn’t set out to write for children with the first one. He was writing for his own pleasure, and found he’d written a children’s book,” said Jankel.

A host of novels and picture books would follow; today, the Paddington books have sold more than 35m copies and been translated into more than 40 languages. Jankel said that Paddington at St Paul’s would be the final story, although she added that her father had also written another non-Paddington book.

• This article was amended on November 9 2017, to correct the date of Karen Jankel’s birth.