Rosamunde Pilcher, author of the sweeping, bestselling family saga The Shell Seekers, has died aged 94.

Her son, the author Robin Pilcher, confirmed the news to the Guardian . “She had been in great form up until Christmas, then suffered from bronchitis in the new year, but was always expected to bounce back as before. However, she suffered a stroke on Sunday night and never regained consciousness,” he said.

Robin described Pilcher as “a wonderful, rather alternative-thinking mother – I think she might have liked the description bohemian – who touched and influenced the lives of many of all ages, not only through her writing but through personal friendships”.

“When my eldest son was young, my wife would always drop in on my mother on her way to Dundee. He thought that when she said ‘going to Dundee’, it meant seeing his grandmother, so he called her Dondie. She was called that by grandchildren, great-grandchildren and all their friends. She was Universal Dondie,” he said.

Set between Cornwall and London, and moving from the second world war to the 1980s, Pilcher’s best-known novel, The Shell Seekers, told the story of an artist’s elderly daughter, Penelope Keeling, who discovers that her father’s painting is worth a small fortune. Pilcher’s 14th novel, written when the author was 63, it was published in 1987 and spent 49 weeks in the New York Times bestseller lists. Selling more than 10m copies, it was adapted for television starring Vanessa Redgrave, and was voted one of Britain’s favourite novels in the BBC’s Big Read in 2003.

“Rosamunde Pilcher was groundbreaking as she was the first to bring family sagas to the wider public. Houses full of secrets, families full of lies, beautiful settings, page-turning plots,” said novelist Katie Fforde, who is president of the Romantic Novelists’ Association. “With The Shell Seekers she changed the face of romantic fiction.”

“She was in her nineties, but I think the world is a poorer place without her,” said Sue Fletcher, Pilcher’s editor at Hodder. “She was a wonderful writer. The warmth and humanity of her writing was matched only by the warmth and humanity of her personality. She was so much fun, and a much-loved friend.”

Pilcher followed The Shell Seekers with bestsellers including Coming Home and September, both of which were filmed for television. She announced her retirement at the age of 80, with her final novel, Winter Solstice, topping charts on both sides of the Atlantic. Her books also have a huge following in Germany, where there have been numerous adaptations of her stories and where, according to her literary agent, she was hailed by the culture minister as “the person who has managed to do more than any to mend the relationships between the German and British peoples”.

Born in Lelant on the north coast of Cornwall, Pilcher began writing at the age of seven and published her first story when she was 19. She starting writing for Mills & Boon under the name Jane Fraser in the late 1940s, describing those books to the New York Times as “frightfully wet little novels – romantic stuff with red roses on the cover”. Her first novel as Rosamunde Pilcher, A Secret to Tell, was published in 1955. Today, Rosamunde Pilcher tours are run in Cornwall, taking busloads of tourists to the locations in her books, and more than 60m copies of her books have been sold around the world.