Queen Elizabeth's mother, the most revered member of the British royal family, has been admitted to a London hospital. Queen Mother, who will turn 101 Saturday, is being treated for anaemia.

Given the age of the Queen Mum as she is affectionately known in Britain her health concerns are closely monitored by an anxious press and public.

She was driven from her royal residence at Clarence House, near Buckingham Palace, to London's King Edward the Seventh hospital. There, she walked in unaided.

A spokeswoman for the Queen Mother says she has received blood transfusion to treat her low red blood cell count.

Medical consultant Dr. Charles Cayley says blood transfusion is usually a simple procedure, but given her age, she is being watched closely. "The Queen Mother is a stoical lady and she has been through major surgery in recent years, but it is a serious matter when an elderly person is anaemic and needs a blood transfusion to correct it," Dr. Cayley said. "Whatever the cause, it is always a serious matter."

Her doctors are now focusing on determining the exact cause of the anaemia.

British officials had said Tuesday the Queen Mother was suffering from mild heat exhaustion and had been advised to rest. She will be in the hospital for at least 24 hours. At that time, her progress will be evaluated.

The hope, according to her spokeswoman, is that she will be released in time to attend birthday celebrations at her London residence on Saturday when she turns 101.

Her 100th birthday last year was celebrated amidst lavish outpouring of affection from the British public.

The Queen Mother is generally regarded as the best-loved royal and is revered by the older generations of Britons. This is in sharp contrast to many younger members of her family who have fallen in and out of favour over the years.

For those old enough to remember, the Queen Mother was an inspiration during the Second World War as she defied German bombers by staying in London through the blitz.

Throughout the decades, the Queen Mum has worked to uphold the reputation of the monarchy during a period of immense social change, which has brought about the demise of the old order and the erosion of traditional British class barriers.