Thatcher won three elections between 1979 and decision not to stand for a second party vote in 1990, when it became apparent she wouldn't have the needed votes. Margaret Thatcher was the longest serving Prime Minister in more than 150 years, and alongside Winston Churchill, many consider her to be one of the two most important British political leaders of the twentieth century. | Thatcher won three elections between 1979 and decision not to stand for a second party vote in 1990, when it became apparent she wouldn't have the needed votes. Margaret Thatcher was the longest serving Prime Minister in more than 150 years, and alongside Winston Churchill, many consider her to be one of the two most important British political leaders of the twentieth century. |