Margaret Thatcher is shown as a toddler in this undated photo. Thatcher was the first woman ever to serve as prime minister of Great Britain and the longest-serving British prime minister of the 20th century.

Margaret Hilda Thatcher, née Roberts, as the Conservative candidate for Dartford, Kent, before she married husband Denis.

Conservative candidate Margaret Roberts accompanies four voters on the piano in a song after a brief political argument in the bar of The Bull Inn, Dartford, Kent, England, circa 1950.

Conservative Party leader Margaret Thatcher is shown as 26-year-old Margaret Roberts at the time of her wedding to Denis Thatcher in London, Dec. 13, 1951.

Conservative Party leader Margaret Thatcher poses in a grey chiffon dress in London, circa 1974.

Margaret Thatcher waves outside 10 Downing Street with husband Denis as she takes up her appointment as the United Kingdom's first female Prime Minister, May 4, 1979.

Prime Minister Margaret Thatcher look s on as Lady Diana Spencer arrives on the arm of her father John Spencer during her wedding to Prince Charles at St. Paul's Cathedral in London, July 29, 1981.

Prime Minister Margaret Thatcher tours Port Stanley with her husband Denis during her surprise five-day visit to the Falkland Islands, Jan. 8, 1983.

Prime Minister Margaret Thatcher sits in the drawing room of her official residence at 10 Downing Street in London, circa 1987.

British Prime Minister Margaret Thatcher greets President Ronald Reagan first lady Nancy Reagan at the White House in Washington.

President George Bush and British Prime Minister Margaret Thatcher drive away in a golf cart from the helicopter-landing zone at Camp David, Md., Nov. 24, 1989.

Margaret Thatcher poses for a portrait, circa 1990.

Prime Minister Margaret Thatcher and her cabinet in 1990.

Nelson Mandela shakes hands with British Prime Minister Margaret Thatcher on the steps of No 10 Downing Street in London, July 4, 1990.

Queen Elizabeth II and former British Prime Minister Thatcher arrive at Claridge's in London for a dinner celebrating the Thatcher's 70th birthday.

Former British Prime Minister Margaret Thatcher poses with Chelsea pensioners during the announcement of the naming of the new Margaret Thatcher Infirmary at the Royal Chelsea Hospital, Feb. 14, 2008, in London.