Mary McCartney has admitted she didn't know the severity of her mother's condition, so her death came as a shock.
As the daughter of Paul and Linda McCartney, she knew that her mother was diagnosed with breast cancer but wasn't prepared for her sudden passing in April 1998, aged just 56.
Speaking to The Times newspaper she explained: "I didn't know my mother was going to die.
"When I took those last pictures of her I did them because she was doing a cookbook and we were like, 'Let's do pictures!'
"Fortunately for her she went through her treatment for a couple of years and, yes, it was aggressive treatment, but she was quite lucky in that she looked quite well.
"She managed to go horse riding and be up and about until two days before she passed away. And then she just went quickly. But before that, we weren't living with, 'We know you've got six months to live' or anything like that."
Mary now admits she used to dislike talking about her late mother's condition but over the years she's grown to "acknowledge" talking about it.
"I didn't want to acknowledge it in case it made something bad happen, but actually now I'm quite upfront about it.
"I'm more, 'It's rubbish but we might as well talk about it.' "