Britain's only female prime minister, Thatcher served from 1979 to 1990 as leader of the Conservative Party. She was called the "Iron Lady" for her personal and political toughness.

She enjoyed a close friendship and working relationship with the late U.S. President Ronald Reagan, with whom she shared similar conservative views.

Thatcher retired from public life after a stroke in 2002 and suffered several strokes after that.

She makes few public appearances. Thatcher missed a reception in honor of her 85th birthday hosted by Prime Minister David Cameron in October 2010 and skipped the unveiling of a statue of Reagan in London in July last year.