Baroness Thatcher is recovering at her home in London today after undergoing hospital tests yesterday. She became unwell at a dinner party and was taken to hospital as a precautionary measure on Friday night.
The former prime minister, 82, was released from St Thomas' Hospital, central London, after tests revealed that nothing serious was wrong. Her private secretary, Mark Worthington, described her condition as "comfortable".
Lady Thatcher had been at dinner with friends at the House of Lords when she started to feel unwell. "She felt nauseous and a little faint. Her legs gave way a little bit under her," Mr Worthington said.
Speaking outside her home, Mr Worthington, said: "She's very comfortable at home; she's sitting up in her sitting room and we've all been chatting away. She's on good form – much better. The tests revealed nothing of any substance. It was just one of those things."
Lady Thatcher had not been speaking to anybody on the telephone but was expecting to receive a visit from her daughter, he said. "She's going to have a quiet day and we're going to let her get a bit of rest."
Two Metropolitan Police officers stood guard outside her home in Belgravia, central London.
Lady Thatcher's daughter, Carol, said her mother had been near the House of Lords when she was taken ill. "You can see St Thomas' Hospital from there and very wisely, at her age and with a history of little strokes, they decided to err on the side of caution."
In 2002, Lady Thatcher said she was cutting back on her public engagements and would no longer make speeches, after doctors diagnosed that she had suffered a series of minor strokes.
Charles Moore, a biographer of Lady Thatcher, said she had suffered a "turn" after becoming too hot. "Obviously there is always some concern with someone that age," he said.
The Prime Minister said he was sorry to hear that Lady Thatcher had been ill. "We are encouraged to hear reports that her condition is better and that she will be leaving hospital soon, and I and others wish her well in a very speedy recovery," he said.
The Conservative leader, David Cameron, said: "I was delighted and relieved to hear that Lady Thatcher is now out of hospital. I'm sure the entire country will join me in wishing her a full and speedy recovery."
She last appeared in public three weeks ago when she opened an infirmary for Chelsea pensioners.
Her husband, Sir Denis, died in June 2003, aged 88.