Former British Prime Minister Lady Margaret Thatcher passed away on Monday.
Thatcher was the first woman to hold the top political post in the United Kingdom. She was in the position from 1979 to 1990.
Thatcher's spokesperson Lord Bell said on Monday: "It is with great sadness that Mark and Carol Thatcher announced that their mother Baroness Thatcher died peacefully following a stroke this morning.
"A further statement will be made later."
"We have lost a great leader, a great prime minister and a great Briton," the current British Prime Minister Cameron said after hearing the news.
Cameron was due to hold a joint conference with Spanish Prime Minister Mariano Rajoy in Madrid this afternoon after the two national leaders met for talks over the future of Europe.
However, this did not go ahead.
News agency AFP reported a Downing St spokesperson as saying: "He (David Cameron) is cutting short his trip. He's returning from Madrid, he's expected back later today".
Lady Margaret Thatcher was the first British prime minister to make an official visit to Spain, in 1988.
During the 1982 Falklands War, Margaret Thatcher agonized over Gibraltar's vulnerability to attack from Spain, reported The Guardian in December 2012.
During a press conference on Monday afternoon, Spanish Prime Minister Rajoy outlined the results of his discussions with David Cameron.
"The United Kingdom is a great friend of Spain," he said.
"Together we are stronger."
"From the economic point of view, we have very close links and we will work to strengthen them," said Rajoy of bilateral relations between Spain and United Kingdom.
Speaking about Lady Margaret Thatcher, Rajoy described her legacy as "immensely valuable" for Europe at the present time.
Recalling the difficulties faced by Thatcher when she came into power in 1979, the Spanish leader said that European countries could now learn from the former British prime minister's example.
He said a "large dose of courage" was need to face the problems confronting Europe at the present time.
Rajoy added that his thoughts were with the British people at this time, and that he thought Thatcher would be remembered as one of the great leaders of the twentieth century.
BBC reported the British government as saying on Monday that Lady Thatcher will be accorded the same status of funeral as the Queen Mother and Princess Diana, but will not lie in state, in accordance with her own wishes.