The Queen's 67-year-old sister was taken ill on the island of Mustique, where she had been holidaying for three weeks. After treatment at the island's surgery she was flown by air ambulance to Barbados.
Witnesses said the Princess, 11th in line to the throne, was well enough to walk onto the plane and last night she was said to be in a stable condition. It is understood she has suffered no serious paralysis.
Ken Will, spokesman for the Mustique Company, which runs the island, said: "She was able to walk from her car across the Tarmac to the plane. She was also sitting on the plane, there was no need for a stretcher."
Princess Margaret, four years younger than the Queen, was well known as a heavy smoker who used to get through 60 cigarettes a day, though she has since given up. Cigarette smoking is widely recognised as one of the risk factors associated with strokes.
She has suffered a series of health scares, one of the most serious being in 1985 when she was admitted to hospital for an operation to remove part of her lung. The section removed turned out to be non-malignant.
Despite her operation she failed to give up smoking immediately, although she did cut down to 30 cigarettes a day.
But ill-health has dogged the Princess, who suffered a nervous breakdown in the 70s. In May 1992 she had to cancel several days of engagements with a "feverish cold" and in late November with a "feverish infection". In January 1993 she was admitted to hospital with pneumonia.
In this latest episode, the Princess fell ill while being entertained by friends at their holiday home. Medical staff were immediately called to help her and she was taken to a nearby doctor's surgery for treatment.
The Queen yesterday carried on her normal engagements and made no reference to her sister's condition. Lord Snowdon, from whom the Princess is divorced, was said to be "most concerned" and has been in touch with the couple's children, Viscount Linley and Lady Sarah Chatto.
The Princess will be flow back to Britain when she is well enough for the long journey.
Loyalty and duty, page 3