She was the first woman prime minister and held office for the Conservatives from 1979 to 1990. Current PM David Cameron said: “I believe she will go down as the greatest British peacetime prime minister
“Margaret Thatcher succeeded against all the odds. The real thing is she didn’t just lead our country; she saved our country.”
And Baroness Thatcher’s former press secretary Sir Bernard Ingham, said: “I think that the country has lost its outstanding Prime Minister of the 20th century.
“She was an outstanding woman and an outstanding Prime Minister.”
Mrs Thatcher came to power as the Winter of Discontent came to end in 1979.
The so called Iron Lady was given the name after she took on the then all powerful trade unions.
Her supporters said she put the “Great” back into Great Britain making the country a powerful international force once more, during a time of frequent disruptive industrial action.
And her opponents blamed her for the creation of a brutal uncaring political philosophy - Thatcherism.
She was also the first leader to win three General Elections in a row.
In 1982 she went to war with Argentina when they invaded the Falklands Islands.
Mrs Thatcher’s response was to send a task force 8,000 miles to South America to reclaim the Islands.
Her government was also responsible for privatising state run industries, including British Gas and British Telecom, allowing the electorate to buy shares in the companies.
She also introduced policy which allowed thousands of people the chance to buy their own council house - people who previously would have had little or no chance of owning their own homes.
In 1984-5 she took on the Mine Workers’ Union and their president Arthur Scargill during the year long nationwide strike.
There were violent clashes between police and striking pickets and many of the mining communities, hit by job losses and pit closures, never recovered from being crushed by the government and Mrs Thatcher’s stance.
But Mrs Thatcher had won this and her battles with the once powerful unions were all but over.
The Tory party introduced eight employment-related acts between 1970 and 1990 - all hitting union power.
Also her attempts to bring peace in Northern Ireland failed - due to heavy Unionist opposition.
And in 1984 Mrs Thatcher survived an IRA attack in a Brighton hotel during the Conservative party conference- five people died in the blast.
But in her own unshakable style, hours after the attack in a keynote conference speech, she said: “This attack has failed. All attempts to destroy democracy by terrorism will fail.”
By 1987 Mrs Thatcher won a third term as prime minister - the first time this had happened at a general election.
She then decided to introduce the controversial poll tax or community charge.
The flat-rate tax replaced rates and was a charge for local services not based on the value of the property in which they lived but on the individual. This brought rioters onto the streets in protest.
Mrs Thatcher resigned in 1990 after a year in which her own party began to question her decision making.
The Tories also suffered in party fighting, by-election humiliations and resignations from her cabinet.
Mrs Thatcher was made a Baroness and again split the Labour opposition when newly elected prime minister Tony Blair invited her to Downing Street.
Baroness Thatcher will not be given a state funeral but will be given a funeral with full military honours, having the same status of those of Princess Diana and the Queen Mother.
The ceremony will take place at London’s St Paul’s Cathedral.