LONDON — Margaret Forster, the author of “Georgy Girl’’ and more than 20 other novels, died Monday in a London hospice after suffering from cancer in the spine. She was 77.

Her husband, Hunter Davies, said Mrs. Forster underwent a double mastectomy 40 years ago and recovered fully, but the cancer returned to her back 10 years ago.

“It was bad, but eventually she recovered. At age 50 on her birthday, she got up at 5 [a.m.] and ran up Red Pike mountain and then swam in the lake and came back to the house and brought me tea,’’ he said.

The couple spent much of their time in England’s peaceful Lake District and in London.

The Royal Society of Literature issued a statement describing her as “an extraordinarily prolific and gifted writer of fiction, non-fiction, and literary criticism.’’

“Georgy Girl’’ was made into a hit movie in 1966 starring Lynn Redgrave, Charlotte Rampling, Alan Bates, and James Mason. Mrs. Forster co-wrote the screenplay for the film, which also inspired a bouncy pop tune that captured the exuberance of the times.

Mrs. Forster taught at a girls’ school in north London before she started to write books.

Davies said her novel “How to Measure a Cow’’ will be published in March.