Harry Potter author JK Rowling said it was " painful" that h er mother never knew about her best-selling success.
The writer, whose books have sold in millions around the world and inspired a series of huge hit films about the teenage wizard, described the "g uilt and worry and anxiety" brought o n by her mother's diagnosis with multiple sclerosis.
Rowling talked about the effect of the illness, which killed her mother when she was 45, on Radio 4's Woman's Hour.
She said: " I was a teenager, but yes, it had the most enormous impact on our family life, and my mother, by the time she was diagnosed, she was quite ill. She had been showing symptoms for a few years and didn't know what they were, so by the time she was diagnosed, her health was deteriorating, so it wasn't just the spectre of the unknown, it was dealing with the daily reality of somebody who's starting not to be able to walk as well as they had, and for such an active person that was a real privation."
Asked what her mother would have made of her success, she said: "M y mother was a passionate reader, and she would have been excited whatever I did, if I succeeded at anything, but particularly to be a writer, she would have considered to be a very valuable thing. Yes, she didn't know, she never knew about Harry Potter - I started writing it six months before she died, so that is painful. I wish she'd known."
T he author is the first in a series of guest editors featuring on the long-running radio show at 10am from Monday to Friday this week.