Margaret Thatcher's daughter says she first realized that her mother was having memory problems when the former prime minister struggled to distinguish between the 1982 Falklands War and the conflict in Bosnia.

In an excerpt from her memoir, due to be published next month, Carol Thatcher charts her mother's decline — and describes the day in 2000 that she first understood her mother was being robbed of her memory.

Carol said her mother — who is now 82 — used to have a memory "like a Web site" but that dementia, combined with a series of mini-strokes, had opened "a new and frightening chapter in our lives."

Carol said her mother's memories of the time she spent as Britain's leader from 1979 to 1990 remained among the sharpest.