Baroness Thatcher enjoyed robust health during her term as Prime Minister, but had become increasing frail over the last decade.

Her health was thrust into the global spotlight in 2011 when Meryl Streep starred in a controversial Hollywood film about her.

The Iron Lady drew criticism from Prime Minister David Cameron and others for concentrating on the dementia the former PM has suffered after a series of small strokes.

Lady Thatcher made her first concession to increasing age in 2002 when she cut back her workload on the advice of doctors.

Concern about the former premier's health had already been growing at that time after it was disclosed she had suffered a minor stroke shortly before New Year 2002 during her golden wedding anniversary holiday with Sir Denis Thatcher in Madeira.

The trip was a nostalgic return visit to the island where they spent their honeymoon in 1951.

She appeared frail and woebegone at Sir Denis's funeral in 2003, and afterwards she appeared less and less frequently in the House of Lords.

In May 2004, the 25th anniversary of her election as Prime Minister, she defied doctors' orders to speak robustly at a dinner held in her honour, attacking the Blair Government and praising Michael Howard, then Tory leader.

There was another health scare in March 2008. Lady Thatcher succumbed to the heat at a dinner in the House of Lords and fainted. She was taken to nearby St Thomas's Hospital for tests, but was allowed to go home the following day.

That year her daughter Carol Thatcher also admitted that her mother suffered from dementia. She said she first noticed her mother's previously formidable memory was failing in 2000.

In her book, A Swim-On Part In A Goldfish Bowl, she said the former Prime Minister had to be repeatedly reminded about the death of her husband Sir Denis, each time reacting to the sad news as if it were the first time she had heard it.

In 2010, she was not well enough to attend an 85th birthday party thrown for her by Mr Cameron at 10 Downing Street.

And last summer she was unable to attend a lunch with former and serving prime ministers hosted by the Queen as part of her Diamond Jubilee celebrations.

But in October last year, she was sufficiently well to mark her 87th birthday with lunch at a restaurant in London with her son Mark and his wife.

However, she was back in hospital last December when she underwent an operation to remove a bladder growth.

As Prime Minister, Baroness Thatcher resolutely bounced back from the small health setbacks she suffered.

In August 1986, she underwent an operation for a condition known as Dupuytren's contracture, which was clawing the little finger of her right hand towards the palm.

Experts say the condition can result from too much hand-shaking, or even too much caning on the hand at school. Although her arm was heavily bandaged after the operation, the then Prime Minister was back at her desk within hours.

Unlike her predecessor at 10 Downing Street James Callaghan, Mrs Thatcher did not have a doctor accompanying her on foreign trips.

Once, when she was asked by Lee Kuan Yew, who was prime minister of Singapore, why she did not travel with a doctor, she replied: "I would have ended up looking after the doctor."