LONDON: Former British Prime Minister Margaret Thatcher is suffering from dementia, a new book by her daughter has revealed. In her book, Carol Thatcher has described in moving detail her mother's gradual loss of memory which began in 2000 and the 'Iron Lady' of Britain's struggle to remember even the simplest facts in her life. "I had always thought of her as ageless, timeless and 100 per cent cast-iron damage-proof," Carol wrote in her memoir A Swim-On Part in the Golden Bowl , serialised by the Daily Mail newspaper. She has recalled how she first noticed slips in her 82-year-old mother's memory during a luncheon meeting in 2000 when Thatcher suddenly got confused between the Falklands and Bosnia while talking about the war in the former Yugoslavia. "It's not always easy to make lunchtime conversation with a mother who for decades has had international leaders and statesmen to engage with in potentially world-changing discussions. "But she soon became confused, and a few sentences later discussion of Bosnia had moved to the Falklands as she muddled the Falklands conflict with the Yugoslav wars. I almost fell off my chair. Watching her struggle with her words and her memory, I couldn't believe it," Carole wrote. Carol, a journalist by profession, has also disclosed how she had to repeatedly break the "truly awful" news of the death her father Sir Denis in 2003 until the information sank in finally. "I had to keep giving her the bad news over and over again. Every time it finally sank in that she had lost her husband of more than 50 years, she'd look at me sadly and say 'Oh' as I struggled to compose myself. "'Were we all there?' she'd ask softly," Carol wrote in her book. She has also recalled how when a friend asked her mother about Soviet leader Mikhail Gorbachev, "she snapped back into Iron Lady mode and was utterly engaging". Thatcher was Britain's first and so far the only female Premier who was in office between 1979 and 1990.